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Abstract:

Polymeric ionic liquids, methods of making and methods of using the same
are disclosed.

Claims:

1. A polymeric ionic liquid (PIL) comprising: i) a cationic component
comprised of an ionic liquid (IL) that is polymerized, and ii) one or
more anionic components, wherein the anionic components can be the same
or different.

2. A mixture comprising one or more of: i) mixtures of PILs, ii) mixtures
of PILs and neat ILs, iii) mixtures of PILs and at least one organic
solvent, iv) mixtures of PILs, ILs, and at least one organic solvent, iv)
mixtures of PILs, ILs, at least one organic solvent, and at least one
other polymeric system, including, but not limited to PDMS, PEG, PA, and
silicone oils.

4. The PIL of claim 1, wherein the cationic component is described by the
general formula of --X +RR'R'', where X is N, P, and As, and where
each of R, R', R'' is selected from the group consisting of proton,
aliphatic group, cyclic group and aromatic group, optionally, wherein the
R, R' and R'' are different from each other.

5. The PIL of claim 1, wherein the cationic component is described by the
formula of (--X(R)3)+, wherein R is proton, aliphatic group
(e.g., propyl, butyl), cyclic group (e.g., cyclohexane) and aromatic
group (e.g., vinyl, phenyl).

6. (canceled)

7. (canceled)

8. (canceled)

9. (canceled)

10. (canceled)

11. (canceled)

12. The PIL of claim 1, wherein the cationic component comprises one or
more of: VHIM+; VDDIM+, VHDIM+, BBIM+.

14. A method for preparing a polymeric ionic liquid (PIL) of claim 1,
comprising reacting an ionic liquid monomer (IL) with RX to form a
polymer, and using a metathesis anion exchange used to exchange the
halide anion with the NTf.sup.- anion.

15. (canceled)

16. (canceled)

17. (canceled)

18. (canceled)

19. (canceled)

20. (canceled)

21. The PIL of claim 1, synthesized by free radical polymerization of one
or more of: 1-vinyl-3-hexylimidazolium chloride,
1-vinyl-3-dodecylimidazolium bromide, and 1-vinyl-3-hexadecylimidazolium
bromide.

24. The PIL of claim 1, wherein the anionic group comprises a taurate
component.

25. (canceled)

26. (canceled)

27. A solvent comprising: at least one PIL of claim 1, and having a
solid/liquid transition temperature is about 400.degree. C. or less and
having a liquid range of about 200.degree. C. or more.

28. (canceled)

29. A device comprising one or more PILs functionalized to (1)
selectively extract one or more analytes of interest and to allow all
other analytes to be removed so that one or more pre-concentrated
analytes can be separated, identified and/or quantified; and/or (2) to
selectively extract all other molecules so that the analyte(s) of
interest can be removed from other molecules thereby allowing them to be
separated, identified, and/or quantified.

30. (canceled)

31. (canceled)

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. (canceled)

38. (canceled)

39. (canceled)

40. (canceled)

41. (canceled)

42. (canceled)

43. (canceled)

44. (canceled)

45. (canceled)

46. (canceled)

47. (canceled)

48. (canceled)

49. A device comprising a polymeric ionic liquid (PIL) polymerized on a
surface of a solid support, wherein the polymerized ionic liquid (PIL) is
adaptable to desorption after exposure to one or more analytes.

50. The device of claim 49, wherein the IL is polymerized by reaction of
at least one free silanol group on the surface of a fused silica support
with at least one vinyl-terminated organoalkoxysilane.

51. The device of claim 49, wherein the IL comprises one or more of:
vinyl-substituted IL monomers and/or crosslinkers, coated on the support
with an initiator and heated to induce free radical polymerization.

62. A separation device comprising an absorbent or absorbent coating
comprised of at least one polymeric ionic liquid (PIL) coated onto a
support, wherein the support comprises one or more of: a solid fused
silica support, a stir bar, a fiber, a film, a membrane, a fibrous mat, a
woven or non-woven material.

63. (canceled)

64. A device for sequestration and/or absorbance of CO2, comprising
at least one PIL of claim 1 on a support.

65. A process of CO2 capture, comprising using at least one PIL of
claim 1.

66. The process of claim 64, including being reversible by heating the
PIL to temperatures around 70-110.degree. C.

67. A device comprising at least one PIL of claim 1, on a support, and
capable of an on-support metathesis exchange of anions from an
immobilized PIL absorbent material.

68. The device of claim 67, wherein the PIL is at least partially
crosslinked to allow swelling of the PIL for complete metathesis
exchange.

69. A device for extraction of one or more of DNA, RNA, protein, nucleic
acids, peptides, amino acids, cellular extracts and portions thereof,
comprising at least one PIL of claim 1 on a support.

70. The sequestration method of claim 64, comprising bringing at least
one of a reactant gas mixture including carbon dioxide contact with a
polymerized ionic liquid (PIL) carbon sequestration catalyst at a
temperature wherein a solid carbon deposit is formed at the surface of
the PIL carbon sequestration catalyst.

71. The method of claim 70, wherein the PIL comprises: i) a cationic
component comprised of an ionic liquid (IL) that is polymerized, and ii)
one or more anionic components, wherein the anionic components can be the
same or different.

72. The method of claim 70, further including recapturing sequestered
CO2 and reusing the PIL carbon sequestration catalyst.

73. A method of separating one chemical from a mixture of chemicals
comprising the steps of: i) providing a mixture of at least one first and
at least one second chemical; ii) exposing the mixture to at least one
solid support including at least one PIL adsorbed, absorbed or
immobilized thereon; and, iii) retaining at least a portion of the first
chemical on the solid support for some period of time.

74. (canceled)

75. (canceled)

76. (canceled)

77. (canceled)

78. (canceled)

79. A method for producing an absorbent material for solid phase
microextraction, comprising: polymerizing one or more ionic liquid (IL)
monomers to produce a polymeric ionic liquid (PIL) material, and forming
at least a partial coating of the PIL material on a support, wherein the
PIL material substantially resists large viscosity drops with elevated
temperatures, and exhibits thermal stability.

80. (canceled)

81. (canceled)

82. (canceled)

83. (canceled)

84. The method of claim 79, wherein the PIL comprises one or more of
non-molecular ionic solvents, the solvent being comprised of at least one
asymmetric cation paired with at least one anion.

85. The method of claim 79, further including tuning one or more of
chemical and physical properties of the PIL through one or more of: i)
choice of the anion, and ii) modification of the cation structure.

86. (canceled)

87. (canceled)

88. (canceled)

89. (canceled)

90. The method of claim 79, further including forming a mixture of PIL
and one or more extraction additives or phase modifiers that aid in
selectively increasing extraction efficiency or promoting wetting of
glass or metal substrates.

91. The method of claim 90, wherein the extraction additives or phase
modifiers comprise one or more of: micelles, monomer surfactants,
cyclodextrins, nanoparticles, synthetic macrocycles, or other polymer
aggregates.

92. The method of claim 79, wherein the support comprises one or more
fibers, stir bars, fused silica capillaries, fused silica supports, small
inner diameter fused silica supports, and combinations thereof, at least
partially coated with at least one PIL.

97. The solid phase microextraction material of claim 96, further
including a support at least partially coated with the polymeric ionic
liquid.

98. The solid phase microextraction material of claim 97 wherein the
support comprises one or more fibers at least partially coated with the
polymeric ionic liquid.

99. (canceled)

100. (canceled)

101. The solid phase microextraction material of claim 97, wherein one or
more of chemical and physical properties of the PILs are capable of being
tunable through choice of anion and/or modification of the cation
structure.

102. (canceled)

103. The solid phase microextraction material of claim 102, wherein a PIL
coating material includes one or more extraction additives or phase
modifiers that aid in selectively increasing the extraction efficiency or
promoting wetting of glass or metal substrates wherein the extraction
additives or phase modifiers comprise one or more of: micelles, monomer
surfactants, cyclodextrins, nanoparticles, synthetic macrocycles, or
other polymer aggregates.

104. A method for extraction of one or more samples, wherein the samples
are solid, liquid, or gas comprising using a solid phase microextraction
(SPME) material comprising one or more polymeric ionic liquids (PILs).

105. The method of claim 104, wherein the SPME material is capable of use
in remote field analysis.

106. (canceled)

107. A method for producing an absorbent material for solid phase
microextraction (SPME), comprising: polymerizing one or more ionic liquid
monomers to produce a polymeric ionic liquid (PIL) absorbent material,
and forming at least a partial coating of the PIL absorbent material on a
support, wherein the PIL absorbent material resists large viscosity drops
with elevated temperatures, and exhibits thermal stability.

128-129. (canceled)

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS AND STATEMENT REGARDING SPONSORED
RESEARCH

[0001] The present application is a continuation-in-part of the Armstrong,
Anderson, U.S. Ser. No. 11/701,537 filed Jan. 31, 2007 [US Pub. No.
2008/0027231 published on Jan. 31, 2008], which is a continuation-in-part
of the Armstrong, Anderson, U.S. Ser. No. 11/187,389 filed Jul. 22, 2005
[US Pub. No. 2006/0025598 published on Feb. 2, 2006] which claims
priority to provisional U.S. Ser. 60/590,857 filed Jul. 23, 2004, which
are expressly incorporated herein, by reference, in their entireties. The
present application also claims the benefit of the provisional patent
application Ser. No. 61/087,411 filed Aug. 8, 2008 which is also
expressly incorporated herein, by reference, in its entirety.

BACKGROUND OF THE INVENTION

[0003] There is no admission that the background art disclosed in this
section legally constitutes prior art. Solid phase microextraction (SPME)
is a popular solvent-free sampling technique developed by Pawliszyn and
co-workers in the early 1990s [1-3]. SPME has gained widespread
acceptance and use in laboratories due to the fact that it is a
solvent-less extraction technique, its mode of operation is relatively
simple and easy to automate, and sampling and sample preparation are
combined into one single step.

[0004] SPME consists of a fiber that is coated with a stationary phase
material, typically composed of a liquid polymer, solid sorbent, or a
mixture of both. Equilibrium is established between an analyte and the
coating material when the fiber is exposed to a solution, which allows
the technique to be applied to both headspace and direct-immersion
sampling. When SPME is coupled with gas chromatography (GC), the analytes
are desorbed from the fiber coating by thermal desorption in the
injection port of the GC.

[0005] The development of new coating materials for SPME has flourished in
the past decade as the technique continues to gain wide-spread popularity
[4-7]. The need for new coating materials is underscored by the fact that
SPME methods must achieve high sensitivity and selectivity. The coating
material must be designed to be resistant to extreme chemical conditions,
such as pH, salts, organic solvents, and modifiers.

[0006] To achieve long fiber lifetimes, the coating should be thermally
stable to avoid excessive losses during the high temperature desorption
step, while also maintaining physical integrity of the film.

[0007] As SPME methods become more developed in sampling complicated
environmental and biological matrices, structural tunability is a
desirable means of modulating specific properties of the coating material
while retaining others.

[0008] Further, a major challenge facing the world today is the
development of a sustainable civilization. An integral component to
maintaining sustainability lies with the replacement of polluting
processes by benign or "green" alternatives. As industrial practices
investigate new green processes, key variables such as cost, feasibility,
and significance of improvements are all considerations that influence
the adoption of any feasible process.

[0009] Description and Properties of Ionic Liquids (ILs)

[0010] Ionic liquids (ILs) are a class of compounds that can be tailor
synthesized to exhibit unique solvent properties while retaining many
green characteristics. Despite widespread interest in ILs, there continue
to be many properties of ILs that are not well-understood. Paramount of
these properties is how the structures of the cationic and anionic
moieties comprising the IL influence the partitioning behavior of various
molecules. No single study or collection of studies performed to this
date can be used to conclusively predict or explain the role of the IL
cation and/or anion on the observed partitioning behavior.

[0012] ILs have negligible vapor pressures at room temperature, possess a
wide range of viscosities, can be custom-synthesized to be miscible or
immiscible with water and organic solvents, often have high thermal
stability, and are capable of undergoing multiple solvation interactions
with many types of molecules. The plethora of interaction capabilities
ILs are capable of undergoing include: hydrogen bond acidity, hydrogen
bond basicity, π-π, dipolar, and dispersion interactions. These
interactions are directly related to the structures of the
cationic/anionic moieties that comprise the IL.

[0013] The aforementioned properties have made molten organic salts [9-11]
and imidazolium and pyrrolidinium-based ILs [12-16] an interesting and
useful class of stationary phase materials in GC. In particular, it has
been shown that the separation selectivity and thermal stability can be
altered by changes to the cation and/or anion, [12-13] polymerization and
immobilization of the IL [15], and by blending different ILs to form
stationary phases with varied composition [16]. While a series of reports
have described the use of ILs in single drop microextraction (SDME)
[17-18] and liquid phase microextraction (LPME) [19-21], only two reports
have studied the use of ILs in SPME [22-23].

[0014] Liu and co-workers reported the development of a disposable IL
coating for the headspace extraction of benzene, toluene, ethylbenzene,
and xylenes [22]. The resulting fibers possessed comparable recoveries to
the commercial fibers coated with polydimethylsiloxane (PDMS).

[0015] To allow for a better wetting and increased loading of the IL on
the fused silica fiber, Hsieh and co-workers utilized a Nafion membrane
followed by dip coating of the SPME fiber in an IL [23]. The fibers were
used to extract polycyclic aromatic hydrocarbons (PAHs) from aqueous
solution. Using GC-MS, detection limits of around 4-5 ng L-1 were
obtained with relative standard deviations ranging from 6-12%. In both of
these reports, the IL had to be re-coated on the fiber after each
extraction and desorption step, which significantly reduces the
convenience and high-throughput nature inherent to SPME.

[0016] It has been observed that many classes of neat ILs have a strong
propensity to flow off the fiber when employing moderate to high
desorption temperatures (200° C. and above) and desorption times
of 4 minutes or longer. Several complications arise from the loss of the
IL during the desorption step: (1) a compromise between the desorption
time and temperature must be achieved; (2) due to the fact that the IL
drips into the injection port and contaminates the liner, it must be
constantly removed and cleaned to prevent unwanted IL-decomposition
products to appear as chromatographic ghost peaks; and, (3) the SPME
fiber needs to be re-coated with the IL, thereby making it inconvenient
while also decreasing fiber-to-fiber reproducibility.

[0017] Due to the negligible vapor pressure inherent to ILs, ILs are not
lost at high temperatures and may be recovered and re-used, demonstrating
their potential as green solvents. In addition, the implementation of
processes using many classes of ILs may minimize the potential for
explosions due to the lack of flashpoint and reduced flammability of many
ILs. Numerous reports have demonstrated enhanced reaction kinetics and
favorable product ratios when performing various organic reactions in an
IL instead of traditional organic solvents.

[0018] Uses of Ionic Liquids in Analytical Extractions

[0019] The initial impetuses for the widespread interest in ILs were
organic synthesis and the growth of green chemistry. Research interest in
ILs has extended into many fields of science involving an
interdisciplinary group of researchers. The numbers of publications
examining basic properties and novel applications of ILs have increased
over 850% from 2000 to 2006. The study and applications involving ILs in
analytical chemistry has been lagging despite the vast opportunities
offered by these designer solvents.

[0020] In an attempt to better understand the solvation properties of ILs,
prior studies have set out to compare the partitioning behavior of
neutral, amino-aromatic compounds, and compounds containing mixed acidic
and basic functionality in octanol/water and ionic liquid/water systems.
While the aforementioned compounds seemed to correlate well between the
two systems, a considerable divergence was noted for acidic compounds as
well as a strong pH dependence on overall partitioning. Other studies
have explored the partitioning of metal ions by task-specific ILs, the
use of ILs as extraction media in deep desulfurization of diesel fuels,
as well as the use of extractants to remove ions from aqueous solutions.

[0021] However, no single study or collection of studies can be used to
conclusively predict or explain the role of the IL cation and/or anion on
the observed partitioning behavior. Due to recent rapid advances in IL
synthesis, it has been proposed that the extensive range of available
cations and anions could produce up to 1018 different ILs. A
relationship between the structure of ILs and their corresponding
physicochemical and solvation properties is desperately needed to
intelligently design new classes of ILs for specific applications.

[0022] Task-Specific Ionic Liquids

[0023] The term "task-specific ionic liquids" (TSILs) relates to salts
that incorporate functional groups into one or both of the ions to impart
specific interactions with dissolved substrates; e.g., the use of urea,
thiourea, and thioether functional groups to remove Hg2+ and
Cd2+ from aqueous solutions. In another example, the reactive
capture of CO2 was demonstrated by a TSIL containing a tethered
amine group. The amine sequesters CO2 through the formation of an
ammonium carbamate complex with the TSIL. While many of these elegant
compounds have been studied in synthetic reactions and in large scale
extraction processes, there has been little work that investigates the
incorporation of these compounds into task-specific microextraction
devices or applications in other areas of separation science.

[0025] Solid phase microextraction (SPME) and stir bar sorptive extraction
(SBSE) are two solvent-free sampling techniques in which sampling and
sample preparation are combined into one single step. SPME consists of a
fused silica fiber that is coated with an absorbent or adsorbent coating
material, typically polydimethylsiloxane (PDMS), polyacrylate, or
carbowax divinylbenzene. Depending on the mode of extraction (headspace
or direct immersion), the analytes are sampled due to their partitioning
to the coating material, typically under equilibrium conditions. The
analytes are desorbed from the fiber using either thermal desorption
(i.e., injection port of a gas chromatograph) or by solvent desorption
(i.e., solvent chamber coupled to a high performance liquid
chromatograph).

[0026] SBSE operates in a similar manner to SPME but differs in the type
of support and the amount of coating material employed in the extraction.
In SBSE, the analytes are extracted into a thick polymer coating on a
magnetic stir bar. The amount of coating material in SBSE is
˜50-250 times larger than SPME, which produces a distinct
sensitivity enhancement.

[0027] Polymer coating materials used in SBSE have largely focused on
PDMS, although there has been a report of incorporating sol-gel
technology into the PDMS coating material. The development of new coating
materials for SPME has flourished in the past five years as the technique
has gained wide-spread popularity.

[0028] As described above, only two reports have studied the use of ILs in
SPME. In both cases, several ILs were chosen and coated on the support to
carry out the extraction. Both reports indicated the extraction
efficiencies obtained were superior to commercial SPME coating materials.
No reports have yet used IL-SPME for the determination of analyte
partition coefficients. There have also been no studies reported on the
use of TSILs in SPME. Moreover, to the best of the inventors' knowledge,
no SPME or SBSE coating material has yet been shown to effectively
extract nucleic acids, which has tremendous opportunity in all aspects of
bioscience.

[0029] There is a need for new coating materials which is underscored by
the fact that SPME methods must achieve high sensitivity and selectivity.
In addition, the coating material must be designed to be resistant to
extreme chemical conditions, such as pH, salts, organic solvents, and
modifiers. Additionally, the coating must be thermally stable to maintain
physical integrity during the lifetime of the fiber.

[0030] There is a further need for ILs that possess the ability to be
structurally tuned to effectively meet any physical or chemical
requirements.

[0031] There is also a need for improved solvent-free sampling techniques.
In particular, there is a need for improved the solid phase
microextraction (SPME) methods.

SUMMARY OF THE INVENTION

[0032] The present invention is based, at least in part, on the inventors'
discovery of the ion exchange mechanism occurring between IL-based
materials and aqueous solutions of nucleic acids. The inventors'
discovery provides a fundamental understanding into the preferential
extraction of biomolecules. In addition, the inventors' discovery is
especially useful in the realm of ionic liquids and separation science,
particularly in the areas of biology and biochemistry, and in the general
environmentally sustainable areas.

[0033] In a first broad aspect, there is provided herein a polymeric ionic
liquid (PIL) comprising: i) a cationic component comprised of an ionic
liquid (IL) that is polymerized, and ii) one or more anionic components,
wherein the anionic components can be the same or different.

[0034] In another broad aspect, there is provided herein a mixture
comprising one or more of: i) mixtures of PILs, ii) mixtures of PILs and
neat ILs, iii) mixtures of PILs and at least one organic solvent, iv)
mixtures of PILs, ILs, and at least one organic solvent, iv) mixtures of
PILs, ILs, at least one organic solvent, and at least one other polymeric
system, including, but not limited to PDMS, PEG, PA, and silicone oils.

[0036] In certain embodiments, the cationic component is described by the
general formula of --X+RR'R'', where X is N, P, and As, and where
each of R, R', R'' is selected from the group consisting of proton,
aliphatic group, cyclic group and aromatic group.

[0037] In certain embodiments, the cationic component is described by the
formula of (--X(R)3)+, wherein R is proton, aliphatic group
(e.g., propyl, butyl), cyclic group (e.g., cyclohexane) and aromatic
group (e.g., vinyl, phenyl). For example, in certain embodiments, the R,
R' and R'' are different from each other.

[0042] In certain embodiments, the cationic component comprises an IL
monomer modified through one or more of: incorporation of longer alkyl
chains, aromatic components, and/or hydroxyl-functionality. Non-limiting
examples include where cationic component comprises one or more of:
VHIM+; VDDIM+, VHDIM+, BBIM+,

[0043] In addition, other non-limiting examples include where the PIL
includes one or more of: poly(VHIM+ NTf2.sup.-);
poly(VDDIM+ NTf2.sup.-), poly(VHDIM+ NTf2.sup.-),
poly(BBIM+ NTf2.sup.-), poly(BBIM+ taurate.sup.-),
poly(BBIM+ A.sup.-).

[0044] In another broad aspect, there is provided herein a method for
preparing a polymeric ionic liquid (PIL), comprising reacting an ionic
liquid monomer (IL) with RX to form a polymer, and using a metathesis
anion exchange used to exchange the halide anion with a counter anion.

[0045] In certain embodiments, the PIL can be synthesized by free radical
polymerization. In other embodiments, the PIL can be synthesized by a
polymerization reaction involving one or more functional group attached
to an aromatic ring of the cationic component. Non-limiting examples
include where the polymerization reaction includes one or more of:
cationic and anionic chain growth polymerization reactions, Ziegler-Natta
catalytic polymerization, and step-reaction polymerization; use of two
different monomers to form copolymers through addition and/or block
copolymerization.

[0046] In another non-limiting example, the PIL can be synthesized using a
condensation polymerization to connect through functional groups such as
amines and alcohols. In another example, the PIL can be synthesized using
a cross-linking reaction.

[0047] In a specific example, the PIL can be synthesized by free radical
polymerization of an imidazolium salt. Non-limiting examples include
where the PIL is synthesized by free radical polymerization of one or
more of: 1-vinyl-3-hexylimidazolium chloride,
1-vinyl-3-dodecylimidazolium bromide, and 1-vinyl-3-hexadecylimidazolium
bromide.

[0048] In certain embodiments, the anionic group comprises one or more of:
carboxylate, sulfate or sulfonate groups which may be substituted or
unsubstituted, saturated or unsaturated, linear, branched, cyclic or
aromatic.

[0049] In certain embodiments, the anionic group comprises an amino acid
component, bis[(trifluoromethyl)sulfonyl]imide, or any anion containing
i) fluorine groups and ii) primary, secondary, or tertiary amine groups.
In a specific example, the anionic group comprises a taurate component.

[0050] In certain embodiments, the PILs have a solid/liquid transition
temperature of about 400° C. or less.

[0051] In certain embodiments, the anionic component is exchanged through
biphasic anion metathesis with one or more of the cationic components.

[0052] In another broad aspect, there is provided herein a solvent
comprising: at least one PIL and having a solid/liquid transition
temperature is about 400° C. or less and having a liquid range of
about 200° C. or more.

[0053] In another broad aspect, there is provided herein a device useful
in chemical separation or analysis comprising: a support and at least one
PIL adsorbed, absorbed or immobilized thereon.

[0054] In another broad aspect, there is provided herein a device
comprising one or more PILs functionalized to: (1) selectively extract
one or more analytes of interest and to allow all other analytes to be
removed so that one or more pre-concentrated analytes can be separated,
identified and/or quantified; and/or (2) to selectively extract all other
molecules so that the analyte(s) of interest can be removed from other
molecules thereby allowing them to be separated, identified, and/or
quantified.

[0055] In another broad aspect, there is provided herein a device
comprising coated or immobilized polymeric ionic liquids for solid phase
microextraction (SPME), wherein one or more PILs are used in neat
polymeric form, or mixed with other ionic liquids or polymeric ionic
liquids, solvents, other polymers, including but not limited to PDMS,
PEG, silicone oils, or other chromatographic adsorbent materials.

[0056] In another broad aspect, there is provided herein a device
comprising one or more PILs chemically adsorbed onto a fiber support or
chemically attached by use of any chemical reaction mechanism.

[0057] In another broad aspect, there is provided herein a separation
device comprising a support at least partially coated with one or more
PILs.

[0058] In another broad aspect, there is provided herein a use of the
separation device in one or more of: headspace extraction,
direct-immersion extraction, or membrane protected SPME extraction.

[0059] One non-limiting example includes where the separation device can
be coupled to gas chromatography (GC) in which one or more analytes are
thermally desorbed in a GC injection port.

[0060] Another non-limiting example includes where the separation device
can be coupled to HPLC in which a HPLC mobile phase or buffered component
is used to desorb molecules from the support.

[0061] Another non-limiting example includes where the separation device
can be coupled to capillary electrophoresis (CE) in which a running
buffer from the CE is used to remove analytes from the support.

[0062] Another non-limiting example includes where one or more analytes to
be separated can exist in any forms of matter (solids, liquids, and
gases) and can be of any chemical component (small molecules, ions,
synthetic or natural polymers, macromolecules, biomolecules).

[0063] Another non-limiting example includes where the separation device
can be used for applications in Liquid-phase microextraction and single
drop microextraction.

[0064] Non-limiting examples include one or more of the following: the
solid support is packed in a chromatographic column; the solid support is
a capillary column useful in gas chromatography; the device is usee in
solid phase microextraction (SPME).

[0065] In another broad aspect, there is provided herein a device
comprising an ionic liquid (IL) polymerized on a surface of a solid
support. In certain embodiments, the polymerized ionic liquid (PIL) is
adaptable to desorption after exposure to one or more analytes.

[0066] In certain embodiments, the IL is polymerized by reaction of at
least one free silanol group on the surface of a fused silica support
with at least one vinyl-terminated organoalkoxysilane. In other
embodiments, the IL comprises one or more of: vinyl-substituted IL
monomers and/or crosslinkers, coated on the support with an initiator and
heated to induce free radical polymerization. In a particular embodiment,
wherein the initiator comprises 2,2'-azo-bis(isobutyronitrile) (AIBN).

[0067] In certain embodiments, the degree of crosslinking is modified to
control the consistency of the formed polymer with lower degrees of
crosslinking resulting in a gel-like material. Also, in certain
embodiments, the degree of crosslinking is modified to control the
consistency of the formed polymer with greater degrees of crosslinking
resulting in a more rigid, plastic-like coating. In other embodiments,
the degree of crosslinking is modified to influence one or more of:
mechanism of partitioning, including adsorption versus absorption, and
overall selectivity for targeted analyte molecules.

[0068] Also provided herein is a device configured for thermally desorbing
analytes from the support. In certain embodiments, the device comprises a
solvent desorption device coupled to a high performance liquid
chromatography column (HPLC).

[0069] In another broad aspect, there is provided herein a separation
device comprising an absorbent or absorbent coating comprised of at least
one polymeric ionic liquid (PIL) coated onto a support.

[0070] In certain embodiments, the separation device can comprise one or
more of the following: a stationary phase coating on the support; a
stationary phase coating coatings for useful for microextractions; a
coating for solid phase microextraction (SPME); a support comprising one
or more of: a solid fused silica support, a stir bar, a fiber, a film, a
membrane, a fibrous mat, a woven or non-woven material.

[0071] In another broad aspect, there is provided herein a method
comprising mixing one or more PILs with one or more solvents to vary the
viscosity and surface tension of the PIL. In certain embodiments, the
method can further include allowing the PIL to be suspended from a
microsyringe configured for sampling of one or more analyte.

[0072] In certain embodiments, at least one suspended drop is used to
sample an analyte matrix (liquid, solid, or gas) and wherein the PIL is
directly injected into a GC, HPLC, or CE or mixed with a solvent and then
directly injected into GC, HPLC, or CE.

[0073] In certain embodiments, the analytes to be separated can exist in
any forms of matter (solids, liquids, and gases) and can be of any
chemical component, including, but not limited to small molecules, ions,
synthetic or natural polymers, macromolecules, biomolecules.

[0074] In another broad aspect, there is provided herein a use of at least
one IL and/or PIL in an extraction process.

[0075] In another broad aspect, there is provided herein a method for
forming a solvent immiscible IL using an in-situ metathesis reaction.

[0076] In another broad aspect, there is provided herein a device for
selective CO2 absorbance, comprising at least one PIL on a support.

[0077] In another broad aspect, there is provided herein a device for
sequestration of CO2, comprising at least one PIL on a support.

[0078] In another broad aspect, there is provided herein a process of
CO2 capture, comprising using at least one PIL as described herein.

[0079] In certain embodiments, the process can include being reversible by
heating the PIL to temperatures around 70-110° C.

[0080] In another broad aspect, there is provided herein a device
comprising at least one PIL on a support, and capable of an on-support
metathesis exchange of anions from an immobilized PIL absorbent material.

[0081] In certain embodiments, the PIL is at least partially crosslinked
to allow swelling of the PIL for complete metathesis exchange.

[0082] In another broad aspect, there is provided herein a device for
extraction of one or more of DNA, RNA, protein, nucleic acids, peptides,
amino acids, cellular extracts and portions thereof, comprising at least
one PIL on a support.

[0083] In another broad aspect, there is provided herein a carbon
sequestration method, comprising bringing at least one of a reactant gas
mixture including carbon dioxide contact with a polymerized ionic liquid
(PIL) carbon sequestration catalyst at a temperature wherein a solid
carbon deposit is formed at the surface of the PIL carbon sequestration
catalyst.

[0084] In certain embodiments, the method can include use of one or more
PILs which comprise: i) a cationic component comprised of an ionic liquid
(IL) that is polymerized, and ii) one or more anionic components, wherein
the anionic components can be the same or different.

[0085] In a particular embodiment, the method further includes recapturing
sequestered CO2 and reusing the PIL carbon sequestration catalyst.

[0086] In another broad aspect, there is provided herein a method of
separating one chemical from a mixture of chemicals comprising the steps
of: providing a mixture of at least one first and at least one second
chemical; exposing the mixture to at least one solid support including at
least one PIL adsorbed, absorbed or immobilized thereon; and, retaining
at least a portion of the first chemical on the solid support for some
period of time. This method can also include where the PIL comprises: i)
a cationic component comprised of an ionic liquid (IL) that is
polymerized, and ii) one or more anionic components, wherein the anionic
components can be the same or different. In certain embodiments, the
method further includes at least one IL liquid mixed with the PIL and
wherein the mixture is immobilized on the solid support.

[0087] In certain embodiments, the solid support is a column and further
comprising and wherein the mixture is passed through the column such that
elution of the first chemical is prevented or delayed. In certain
embodiments, the column is a capillary.

[0088] In certain embodiments, the mixture is carried in a gaseous mobile
phase.

[0089] In another broad aspect, there is provided herein a method for
producing an absorbent material for solid phase microextraction,
comprising: polymerizing one or more ionic liquid (IL) monomers to
produce a polymeric ionic liquid (PIL) material, and forming at least a
partial coating of the PIL material on a support, wherein the PIL
material substantially resists large viscosity drops with elevated
temperatures, and exhibits thermal stability.

[0090] In certain embodiments, the PIL material comprises two or more
polymeric ionic liquids. Also, in certain embodiments, one or more ionic
liquid (IL) monomers can be used to synthesize the PIL using a free
radical reaction.

[0091] In certain embodiments, the PIL material is capable of
incorporating simultaneous solvation interactions, depending on the
analytes being extracted.

[0092] In certain embodiments, the structural design of the PIL is
selected in order to achieve high thermal stability.

[0093] In certain embodiments, the PIL comprises one or more of
non-molecular ionic solvents, the solvent being comprised of at least one
asymmetric cation paired with at least one anion.

[0094] In certain embodiments, the method can further include tuning one
or more of chemical and physical properties of the PIL through one or
more of: i) choice of the anion, and ii) modification of the cation
structure. Non-limiting examples include: where the cation comprises one
or more of: imidazolium-based monomers including functionalized
imidazolium, pyridinium, triazolium, pyrrolidinium, ammonium. Other
non-limiting examples include where the anion comprises one or more of:
Cl.sup.-, Br.sup.-, I.sup.-, bis[(trifluoromethyl)sulfonyl]imide,
PF6.sup.-, BF4.sup.-, CN.sup.-, SCN.sup.-, taurate, and/or
other amino acid groups.

[0095] In certain embodiments, the PIL is substantially free of residual
halides following anion metathesis.

[0096] In certain embodiments, the PIL comprises one or more of:
1-vinyl-3-hexylimidazolium chloride; 1-vinyl-3dodecylimidazolium bromide,
and 1-vinyl-3-hexadecylimidazolium bromide.

[0097] In certain embodiments, the method can further include forming a
mixture of PIL and one or more extraction additives or phase modifiers
that aid in selectively increasing extraction efficiency or promoting
wetting of glass or metal substrates.

[0098] In certain embodiments, the extraction additives or phase modifiers
comprise one or more of: micelles, monomer surfactants, cyclodextrins,
nanoparticles, synthetic macrocycles, or other polymer aggregates.

[0099] In certain embodiments, the support comprises one or more of:
fibers at least partially coated with at least one PIL; stir bar
supports; walls of fused silica capillaries; small inner diameter fused
silica supports.

[0100] In another broad aspect, there is provided herein a stationary
phase microextraction material (SPME) for solid phase microextraction
comprising one or more poly ionic liquids (PILs). In certain embodiments,
the solid phase microextraction material can further include one or more
of: a support at least partially coated with the polymeric ionic liquid;
fibers at least partially coated with the polymeric ionic liquid; fibers
that comprise small inner diameter fused silica fibers.

[0101] In certain embodiments, the solid phase microextraction material
can include ionic liquids that are comprised of one or more of
non-molecular ionic solvents comprised of bulky, asymmetric cations
paired with one or more types of anions. In certain embodiments, one or
more of chemical and physical properties of the PILs are capable of being
tunable through choice of anion and/or modification of the cation
structure.

[0102] In certain embodiments, the PIL coating material includes one or
more extraction additives or phase modifiers that aid in selectively
increasing the extraction efficiency or promoting wetting of glass or
metal substrates. In certain embodiments, the extraction additives or
phase modifiers comprise one or more of: micelles, monomer surfactants,
cyclodextrins, nanoparticles, synthetic macrocycles, or other polymer
aggregates.

[0103] In another broad aspect, there is provided herein a method for
extraction of one or more samples, wherein the samples are solid, liquid,
or gas comprising using a solid phase microextraction (SPME) material
comprising one or more polymeric ionic liquids (PILs). In certain
embodiments, the SPME material is capable of use in remote field
analysis.

[0105] In another broad aspect, there is provided herein a method for
producing an absorbent material for solid phase microextraction (SPME),
comprising: polymerizing one or more ionic liquid monomers to produce a
polymeric ionic liquid (PIL) absorbent material, and forming at least a
partial coating of the PIL absorbent material on a support, wherein the
PIL absorbent material resists large viscosity drops with elevated
temperatures, and exhibits thermal stability. In certain embodiments, the
PIL comprises two or more PILs. Also, in certain embodiments, one or more
PILs are synthesized by a free radical reaction. In certain embodiments,
the PIL absorbent material comprises one or more of non-molecular ionic
solvents comprised of bulky, asymmetric cations paired with at least one
type of anion.

[0106] In certain embodiments, the method can further include tuning one
or more of chemical and physical properties of the PIL through the choice
of anion and/or modification of cation structure. In certain embodiments,
the PIL absorbent material is capable of incorporating simultaneous
solvation interactions, depending on the analytes being extracted. Also,
in certain embodiments, the structural design of the PIL is selected in
order to achieve high thermal stability. In particular embodiments, the
PIL is substantially free of residual halides following anion metathesis.
Non-limiting examples include where bis[(trifluoromethyl)sulfonyl]imide
salts paired with large, bulky cations are used to produce PILs with
thermal stability.

[0108] In certain embodiments, the desorption temperature and desorption
time are optimized to prolong the lifetime of the absorbent material.

[0109] In certain embodiments, the polymeric ionic liquids comprise one or
more of: 1-vinyl-3-hexylimidazolium chloride;
1-vinyl-3-dodecylimidazolium bromide, and 1-vinyl-3-hexadecylimidazolium
bromide.

[0110] In certain embodiments, the PIL absorbent material includes one or
more extraction additives or phase modifiers that aid in selectively
increasing the extraction efficiency or promoting wetting of glass or
metal substrates.

[0111] In certain embodiments, the extraction additives or phase modifiers
comprise one or more of: micelles, monomer surfactants, cyclodextrins,
nanoparticles, synthetic macrocycles, or other polymer aggregates.

[0112] In certain embodiments, the support comprises one or more: fibers
at least partially coated with the PIL material; stir bar supports; walls
of fused silica capillaries; small inner diameter fused silica supports.

[0113] In certain embodiments, the polymeric ionic liquids comprise one or
more of: 1-vinyl-3-hexylimidazolium chloride;
1-vinyl-3-dodecylimidazolium bromide, and 1-vinyl-3-hexadecylimidazolium
bromide.

[0114] In certain embodiments, the solid phase microextraction material is
amenable to hyphenation with high performance liquid chromatography
(HPLC).

[0115] In another broad aspect, there is provided herein a use of PILs in
developing one or more task-specific ionic liquids (TSILs) of
microextraction coatings, chromatographic media, membrane systems, and
chemical sensors.

[0116] In another broad aspect, there is provided herein a process for
polymerizing an ionic liquid (IL), comprising: i) attaching a vinyl (or
allyl) functional group on a ionic liquid molecule; and ii) transforming
the composition of step i) into a polymer in which the unit of
unsaturation is gone, thereby forming a linear polymer.

[0117] In another broad aspect, there is provided herein a process for
polymerizing an ionic liquid salt comprising using one or more of: living
polymerization, condensation polymerization, addition of at least one
crosslinker to an IL monomer solution to form crosslinked or
branched-type polymers.

[0118] In one aspect, there is described herein, the incorporation of
ionic liquids (ILs) and/or polymeric ionic liquid (PILs) materials into
analytical microextractions. Such incorporation allows for the
determination of analyte partition coefficients between these materials
and other solvents, as well as, provides for the development of new,
highly tunable absorbent coatings.

[0119] Described herein is the use of polymeric ionic liquids (PIL) as a
novel class of stationary phase coatings for solid phase microextraction.
The polymerization of IL monomers produces materials that can be coated
as thin films on supports, while resisting large viscosity drops with
elevated temperatures and exhibiting exceptional thermal stability.

[0120] The long lifetime and high thermal stability of the PIL-based SPME
coatings may provide them particular advantages in GC-MS applications
involving highly selective ester and FAME extractions from complex
matrices.

[0121] Among the advantages of the present method are: fast, solvent-free
extraction and one step extraction; the concentration of analytes make
SPME time efficient; the samples can be solid, liquid, or gas; the
compact and portable nature of SPME allows for remote field analysis;
and, the method is amenable to hyphenation with gas chromatography (GC)
and high performance liquid chromatography (HPLC).

[0122] The structure of the IL monomer can be custom designed to
incorporate a multitude of simultaneous solvation interactions depending
on the analytes being extracted and the complexity of the matrix.

[0123] In addition, the ILs described herein possess high thermal
stabilities thereby limiting the bleed of the phase during the desorption
step at high GC injection port temperatures.

[0124] The highly tunable structure of the ILs described herein provides
varied solvation properties allowing for the development of highly
selective coatings.

[0126] In another aspect, there is provided a novel use of polymeric ionic
liquids (PILs) which can be generally described herein as non-molecular
ionic solvents comprised of bulky, asymmetric cations paired with various
anions. The chemical and physical properties of the PILs described herein
are highly tunable through the choice of anion and modification of the
cation structure.

[0127] In another broad aspect, there is provided herein a method of using
ILs as absorbent coatings in solid phase microextraction (SPME). In
particular, there are provided herein PILs that are useful as selective
coatings for solid phase microextraction and for stir bar sorptive
extraction.

[0128] In another aspect, there is provided herein the use of PILs as
selective coatings for the extraction of such analytes as esters using
solid phase microextraction.

[0129] In a particular aspect, the inventors herein now show that by
polymerizing IL monomers to form polymeric ionic liquids (PILs), stable
absorbent coatings are developed for the analysis of esters in red and
white wines as well as for the extraction of benzene, toluene, ethyl
benzene, and xylenes in gasoline.

[0130] The IL monomers and their polymeric analogs (PILs) described herein
possess many unique properties and characteristics that make them
particularly suitable as absorbent coatings for SPME. In one non-limiting
example, PILs can be coupled with GC for the development of extraction
methods for the analysis of such analytes as, for example, esters in red
and white wines, as well as benzenes, toluenes, ethyl benzenes and
xylenes (BTEX) compounds in gasoline.

[0131] The methods described herein exhibit good analyte recovery,
linearity over a wide range of concentrations, high reproducibility, and
good sensitivity. In addition, the sensitivity can be further enhanced
through the use of smaller inner diameter fused silica supports allowing
for thicker coatings.

[0132] These absorbent coatings have particular advantages in GC-MS
applications due to the fact that PIL coatings exhibit long lifetimes,
low levels of thermal bleed, and high selectivity.

[0133] Various objects and advantages of this invention will become
apparent to those skilled in the art from the following detailed
description of the preferred embodiment, when read in light of the
accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0134] `The patent or application file may contain at least one photograph
and/or one drawing executed in color. Copies of this patent or patent
application publication with color drawing(s) and/or photograph(s) will
be provided by the Office upon request and payment of the necessary fee.

[0135] FIG. 1: Illustrates the effect of the cation and anion on the
surface tension for dicationic ionic liquids.

[0136]FIG. 2: Illustrates the effect of the cation and anion on the
density for dicationic ionic liquids.

[0138] FIG. 4: is a positive ion electrospray mass spectrum of mixture 4
indicating the relative abundance of the three substituted dications as
well as the loss of a proton on the imidazolium ring thereby allowing the
formation of the +1 ion.

[0139] FIG. 5: is a plot illustrating the effect of
1-hexyl-3-vinylimidazolium bis[(trifluoromethane)sulfonyl]imidate film
thickness on the peak efficiency (theoretical plates/meter) of
naphthalene at 100° C.

[0145] FIG. 10: The vinyl-substituted ionic liquid (IL) monomer is
prepared by the reaction of 1-vinylimidazole with the corresponding
haloalkane followed by free radical polymerization to form the linear
polymer.

[0146] FIG. 11: Metathesis anion exchange is used to exchange the halide
anion with the NTf.sup.- anion.

[0148] FIGS. 13A-13D: Scanning electron micrographs of a 100 μm inner
diameter bare fused silica support (FIG. 13A) and various angles of the
fused silica support coated with the poly(ViDDIm+ NTf.sup.-) PIL
(FIG. 13B), (FIG. 13C), and (FIG. 13D). The estimated film thickness is
approximately 12-18 μm.

[0149] FIGS. 14A-14B: Sorption time profiles obtained for the
poly(ViHIm+ NTf.sup.-) PIL fiber by extracting the studied analytes
at a concentration of 200 L-1 at varying extraction time intervals
using a constant stir rate of 900 rpm at 23° C.:

[0171] FIGS. 33A and 33B: Schematic illustration showing partitioning
equilibria for an analyte (A) molecule in aqueous solution (S), headspace
(H) and IL coated/immobilized on a solid support (IL): FIG. 33A: A system
in which the IL is coated/immobilized on a fused silica support. FIG.
33B: A system using a glass stir bar support.

[0187] FIG. 49: Sorption-time profile obtained under low pressure of
CO2 showing the comparison of different IL-based sorbent coatings to
2 commercial-based coatings (Carboxen and PDMS). The film thickness of
the two commercial coatings are approximately six to seven times that of
the IL-based systems.

[0188] FIG. 50: Sorption-time profile obtained under high pressure of
CO2 showing the comparison of different IL-based sorbent coatings to
2 commercial-based coatings (Carboxen and PDMS). The film thickness of
the two commercial coatings are approximately six to seven times that of
the IL-based systems.

[0190] FIG. 52: Structures of the ILs and PIL used in the HS-SPME-GC
method. IL (A) was used as high temperature solvent to solubilize the
analytes in the study. PIL (B) was used as a SPME sorbent coating. IL (C)
was used as a low bleed, highly selective stationary phase in GC.

[0193] To overcome the aforementioned challenges while retaining the
unique solvation characteristics of ILs, the inventors herein now
describe the development of polymeric ionic liquids (PILs). The inventors
herein have now discovered that materials coated with such PILs do not
need to be recoated after every extraction, possess exceptional thermal
stability, highly reproducible extraction efficiencies, and long
lifetimes.

[0194] In a broad aspect, there is provided herein a method for producing
polymeric ionic liquids (PILs) using a free radical reaction. In certain
embodiments, the ionic liquids (ILs) comprise one or more of
non-molecular ionic solvents comprised of bulky, asymmetric cations
paired with various anions.

[0195] In certain embodiments, the method further includes tuning one or
more of the chemical and physical properties of ILs and/or PILs through
the choice of anion and modification of the cation structure. The PIL
materials are capable of incorporating simultaneous solvation
interactions, depending on the analytes being extracted. Further, in
certain embodiments, the structural design of the polymeric ionic liquid
can be selected in order to achieve high thermal stability.

[0196] In certain embodiments, the PIL is substantially free of residual
halides following anion metathesis.

[0197] In one example, bis[(trifluoromethyl)sulfonyl]imide salts paired
with large, bulky cations are used to produce IL monomers with
exceptional thermal stability.

[0198] In another example, the PILs can be comprised of one or more of:
imidazolium-based monomers including functionalized imidazolium,
pyridinium, triazolium, pyrrolidinium, ammonium cations with anions
including, but not limited to: Cl--, Br--, I--,
bis[(trifluoromethyl)sulfonyl]imide, PF6--, BF4--, CN--, SCN--. Further,
in certain embodiments, the polymeric ionic liquids comprise one or more
of: 1-vinyl-3-hexylimidazolium chloride; 1-vinyl-3-dodecylimidazolium
bromide, and 1-vinyl-3-hexadecylimidazolium bromide.

[0199] Also provided herein is a method for producing an absorbent
material for solid phase microextraction (SPME) which generally includes
polymerizing ionic liquid monomers to produce an absorbent PIL material,
and forming at least a partial coating of the absorbent PIL material on a
support. The absorbent PIL material resists large viscosity drops with
elevated temperatures, and exhibits thermal stability.

[0200] In certain embodiments, the IL and/or PIL absorbent coating
material includes one or more extraction additives or phase modifiers
that aid in selectively increasing the extraction efficiency or promoting
wetting of glass or metal substrates.

[0201] In certain embodiments, the IL and/or PIL absorbent coating
material can include one or more of: micelles, monomer surfactants,
cyclodextrins, nanoparticles, synthetic macrocycles, or other polymer
aggregates as extraction additives or phase modifiers that aid in
selectively increasing the extraction efficiency or promoting wetting of
glass or metal substrates. Further, in certain embodiments, the
desorption temperature and/or desorption time can be optimized to prolong
the lifetime of the coating material.

[0202] In certain embodiments, the support comprises one or more fibers at
least partially coated with the PIL absorbent material. In certain
embodiments, the support comprises one or more stir bar supports. In
certain embodiments, the support comprises one or more walls of fused
silica capillaries. In certain embodiments, the support comprises small
inner diameter fused silica supports.

[0203] In another broad aspect, there is provided herein a method
extraction of one or more samples where the samples are solid, liquid, or
gas comprising using the PIL SPME as described herein. For example, in
certain embodiments, such PIL SPME materials are capable of use in remote
field analysis. Also, in certain embodiments, the PIL SPME materials are
amenable to hyphenation with gas chromatography (GC).

[0204] The present invention is further defined in the following Examples,
in which all parts and percentages are by weight and degrees are Celsius,
unless otherwise stated. It should be understood that these Examples,
while indicating preferred embodiments of the invention, are given by way
of illustration only. From the above discussion and these Examples, one
skilled in the art can ascertain the essential characteristics of this
invention, and without departing from the spirit and scope thereof, can
make various changes and modifications of the invention to adapt it to
various usages and conditions. All publications, including patents and
non-patent literature, referred to in this specification are expressly
incorporated by reference herein.

Example A

Diionic Salts

[0205] A "diionic salt" or "DIS" is a salt formed between a dication as
described herein and a dianion or two anions or between a dianion as
described herein and a dication or two cations. This term is not meant to
embrace a single species that has a +2 or -2 charge such as Mg+2 or
SO4-2. Rather it contemplates a single molecule with two
discreet mono-ionic groups, usually separated by a bridging group. The
two ionic species should be of the same charge. They may be different
types of groups or the diionic liquid salts may be "geminal" which means
both ionic groups are not only the same charge, but also the same
structure. The counterions need not be identical either. In one
embodiment, either the diion or the salt forming species is chiral,
having at least one stereogenic center. In such instances, the diionic
liquid salts may be racemic (or in the case of diastereomers, each pair
of enantiomers is present in equal amounts) or they may be optically
enhanced. "Optically enhanced" in the case of enantiomers means that one
enantiomer is present in an amount which is greater than the other. In
the case of diastereomers, at least one pair of enantiomers is present in
a ratio of other than 1:1. Indeed, the diionic liquid salts may be
"substantially optically pure" in which one enantiomer or, if more than
one stereogenic center is present, at least one of the pairs of
enantiomers, is present in an amount of at least about 90% relative to
the other enantiomer. The diionic liquid salts of the invention may also
be optically pure, i.e., at least about 98% of one enantiomer relative to
the other. Usually, the term diionic salt is used to describe a salt
molecule, although, as the context suggests, it may be used synonymously
with "diionic liquid" ("DIL") and "diionic liquid salt" (DILS''). A
"diionic liquid" or "DIL" in accordance with the present invention is a
liquid comprised of diionic salts. Thus, sufficient DS molecules are
present such that they exist in liquid form at the temperatures indicated
herein. This presumes that a single DS molecule is not a liquid. A DL is
either a dicationic ionic liquid or a dianionic ionic liquid (a liquid
comprising either dicationic salts or dianionic salts as described
herein). A "dicationic ionic liquid" (used synonymously with "liquid
salts of a dication") in accordance with the present invention is a
liquid comprised of molecules which are salts of dicationic species. The
salt forming counter-anions may be mono-ionic such as, for example only,
Br--, or dianionic, such as, again for example only, succinic acid. Any
dicationic ionic liquid which is stable and has a solid/liquid
transformation temperature of 400° C. or less is contemplated. The
same is true for "dianionic ionic liquids" also known as "liquid salts of
a dianion," except the charges are reversed. Dicationic liquids and
dianionic liquids can also be referred to herein as diionic liquid salts
("DILS" or "DCLS" and "DALS" depending upon charge).

[0206] Preferably, a dicationic ionic liquid or dianionic ionic liquid
will not substantially decompose or volatilize (or remain substantially
non-volatile) as measured by being immobilized as a thin film in a fused
silica capillary or on a silica solid support as described herein, at a
temperature of 200° C. or less. "Substantially" in this context
means less than about 10% by weight will decompose or volatilize at
200° C. inside a capillary over the course of about one hour.
Moreover, the dicationic ionic liquid in accordance with this embodiment
will preferably have either a solid/liquid transformation temperature at
about 100° C. or less or a liquid range (the range of temperatures
over which it is in a liquid form without burning or decomposing) of at
least 200° C.

[0207] In another embodiment, these dicationic ionic liquids will have
both a solid/liquid transformation temperature at about 100° C. or
less and a liquid range of at least 200° C.

[0208] In another aspect of the invention, a dicationic ionic liquid will
not substantially volatilize or decompose, as discussed herein, at a
temperature of less than about 300° C. "Substantially" in this
context means that less than about 10% by weight will decompose or
volatilize at 300° C. inside a capillary over the course of about
one hour. Moreover, the dicationic ionic liquids in accordance with this
embodiment will preferably have either a solid/liquid transformation
temperature at 25° C. or less. In another embodiment, the
dicationic ionic liquids will also have a liquid range of at least
200° C. In an even more preferred aspect of the invention, the
liquid range will be 300° C. or above.

[0209] Preferably, a dianionic ionic liquid will not substantially
decompose or volatilize as measured by being immobilized as a thin film
in a fused silica capillary as described herein, at a temperature of
200° C. or less. Moreover, the dianionic ionic liquid in
accordance with this embodiment will preferably have either a
solid/liquid transformation temperature at about 100 C or less or a
liquid range of at least 200° C.

[0210] In another embodiment, these dianionic ionic liquids will have both
a solid/liquid transformation temperature at about 100° C. or less
and a liquid range (diionic molecule is stable over the entire
temperature range) of at least 200° C.

[0211] In another aspect of the invention, a dianionic ionic liquid will
not substantially volatilize or decompose, as discussed herein, at a
temperature of less than about 300° C. Moreover, the dianionic
ionic liquids in accordance with this embodiment will preferably have
either a solid/liquid transformation temperature at about 25° C.
or less. In another embodiment, the dianionic ionic liquids will also
have a liquid range of at least 200° C. In an even more preferred
aspect of the invention, the liquid range will be 300° C. or
above.

[0212] Thus a diionic liquid in accordance with the present invention is
either a dicationic ionic liquid salt or a dianionic ionic liquid salt
which will neither substantially decompose nor substantially volatilize,
as measured as described herein, as a temperature of 200° C. or
less and will have a temperature of solid/liquid transformation
temperature at 100° C. or a liquid range of at least 200°
C.

[0213] In other aspects of the invention, these diionic liquids will have
both solid/liquid transformation temperature at about 100° C. or
more and a liquid range of at least 200° C.

[0214] In other embodiments in accordance with the present invention, the
diionic liquids, either dicationic ionic liquids or dianionic ionic
liquids will be stable, that is not substantially volatilized or
decomposed, as discussed herein, at a temperature of less than about
300° C. and will have a solid/liquid transformation temperature at
about 25° C. or less. A particular preferred embodiment of this
aspect of the present invention, the diionic liquids will have a liquid
range of at least 200° C. and even more preferably at least
300° C. Any diionic compound which can form a stable liquid salt
that meets the broadest parameters is contemplated.

[0215] In another embodiment, the present invention provides a stable
diionic liquid comprising at least one liquid salt of dianionic molecule
or dicationic molecule of the structure of formula I or II: C-A-B-A' (I)
or C'-A-B-A'-C'' (II) wherein A and A' are ether both anions or both
cations, or are both groups which overall have an anionic or cationic
charge and which may be the same or different, so long as they both have
the same charge (positive of negative); B is a bridging group (also
referred to as a chain or bridging moiety) that may be substituted or
unsubstituted, saturated or unsaturated, aliphatic, including straight or
branched chains, cyclic or aromatic, and which may contain, in addition
to carbon atoms and hydrogen, N, O, S and Si atoms; and C, C' and C'' are
counter ions having a charge which is opposite that of A and A', C' and
C'' are ether both mono-anionic or mono-cationic or groups which have a
single anionic or cationic charge and may be the same or different so
long as they both have the same charge (positive or negative) and C is
ether dianionic or dicationic or contains two groups which each have a
single anionic or cationic charge.

[0216] In another embodiment, A and A' are cationic and are, without
limitation, substituted or unsubstituted, saturated or unsaturated,
aliphatic including straight or branched chain, cyclic or aromatic,
quaternary ammonium, protonated tertiary amine, phosphonium or arsonium
groups. When A and A' are cationic, C' and C'' are anionic counterions
which, without limitation, include halogens, mono-carboxylates
mono-sulfonates, mono-sulphates, NTf2.sup.-, BF4.sup.-, trifilates
or PF6.sup.-, and C is a dianionic molecule having two anionic
groups each selected from, without limitation, carboxylate, sulfate or
sulfonate groups. In another embodiment, A and A' are anionic and are,
without limitation, substituted or unsubstituted, saturated or
unsaturated, aliphatic including straight or branched chain, cyclic or
aromatic, carboxylates, sulfonates, and sulphates. When A and A' anionic,
C' and C'' are cationic counterions which, without limitation, include
quaternary ammonium, protonated tertiary amine, phosphonium or arsonium
groups. C is a dicationic molecule which can be, without limitation, a
compound having two cationic groups each selected from quaternary
ammonium, protonated tertiary amine, phosphonium or arsonium groups. In
another embodiment, these dianionic ionic liquids will have both a
temperature of solid/liquid transformation of about 100° C. or
less and a liquid range of at least 200 degree. C. In a particularly
preferred embodiment, these liquid salts of formula I or II have a
solid/liquid transition temperature of from about 100° C. or less
and/or a liquid range of 200° C. or more and/or are substantially
non-volatile and non-decomposable at temperatures below 200° C.

[0217] Typically, the structural considerations for diionic liquids are
the same whether they are dianionic ionic liquids or dicationic ionic
liquids. First, the diionic liquids will include a diionic species,
either a dianionic or a dicationic molecule. The ionic species are
normally separated by a chain or bridging moiety or group as discussed
herein. Any anion or cation which can provide a dianionic ionic liquid or
dicationic ionic liquid is contemplated. These include those that are
identified above as A and A'. Possible cations include, without
limitation, quaternary ammonium (--N(R)4)+, protonated tertiary
amines (--N(R)3H)+, phosphonium and arsonium groups. These
groups can be aliphatic, cyclic, or aromatic. Examples of aliphatic
ammonium dications are found in EXAMPLE A--Table 2 and examples aromatic
ammonium dications are found in EXAMPLE A--Table 1. Anions may include,
for example, carboxylates, sulphonates, or sulphonates. Examples of a
dicarboxylic acid dianion include, without limitation, succinic acid,
nonanedioic acid, and dodecanedioic acid. Other non-limiting examples of
diionic species (dianions an dications including a generic bridging
group) include:

##STR00001##

[0218] The value of n is discussed in connection with the length of the
bridging group. In addition, hybrid dianions and dications are
contemplated. Thus, for illustration only, a dication can be composed of
a quaternary ammonium group and an arsonium group and a dianion can be
composed of a carboxylate group and a sulphonate. The counter ions may
also be different from each other.

[0219] The bridging group or chain interposed between the two ionic
species can be any length or any composition which affords a diionic
liquid of suitable properties. These include the groups identified as B
above. There are certain factors that should be considered in selecting
such a chain or bridging moiety. First, the larger the diionic molecule
in general, the greater the chance that the melting point or temperature
of solid/liquid transformation will be elevated. This may be less of a
concern where the liquid range need not be extensive and the temperature
of solid/liquid transformation need not be terribly low. If, however, one
desires a liquid range of about 200° C. or more and/or a
solid/liquid transformation temperature at 100° C. or less, the
size of the overall molecule can become a larger and larger factor.
Second, the chain should have some flexibility. An excessive degree of
unsaturated groups, the use of very rigid and/or stericly bulky groups
can adversely impact the ability of the resulting materials to act as
solvents and reduce their overall and utility. Thus, multiple fused ring
structures, such as those found in, for example, cholesterol, and
polyunsaturated aliphatic groups with extensive unsaturation should
generally be avoided.

[0220] In general, the length of the bridging group can range from a
length equivalent to that of a saturated aliphatic carbon chain of
between about 2 and about 40 carbon atoms (e.g., n=C2-C40 when
bridging group is composed of carbon). More preferably, the length should
be approximately that resulting from a saturated aliphatic carbon chain
of about 3 to about 30 carbon atoms in length.

[0221] The chain or bridging group may be aliphatic, cyclic, or aromatic,
or a mixture thereof. It may contain saturated or unsaturated carbon
atoms or a mixture of same with, for example, alkoxy groups (ethoxy,
propoxy, isopropoxy, butoxy, and the like). It may also include or be
made completely from alkoxy groups, glycerides, glycerols, and glycols.
The chain may contain hetero-atoms such as O, N, S, or Si and derivatives
such as siloxanes, non-protonated tertiary amines and the like. The chain
may be made from one or more cyclic or aromatic groups such as a
cyclohexane, a immidazole, a benzene, a diphenol, a toluene, or a xylene
group or from more complex ring-containing groups such as a bisphenol or
a benzidine. These are merely representative and are not meant to be
limiting. Generally, however, the bridging group will not contain an
ionically charged species, other than the dianions or dications.

[0222] The diionic liquids of the present invention are generally salts,
although they may exist as ions (+1, -1, +2, -2) in certain
circumstances. Thus, in most instances, each ion should have a
counterion, one for each anion or cation. Charge should be preserved. In
the case of a dianionic ionic liquid, two cations (including those
identified as C' or C'') (or one dication) (including those identified as
C) are required and in the case of a dicationic ionic liquid, two anions
(including those identified as C' or C'') (or one dianion) (including
those identified as C) are required. The choice of anion can have an
effect of the properties of the resulting compound and its utility as a
solvent. And, while anions and cations will be described in the context
of a single species used, it is possible to use a mixture of cations to
form salts with a dianionic species to form a dianionic ionic liquid. The
reverse is true for dications. For clarity sake, the salt-forming ions
will be referred to as counterions herein.

[0223] Cationic counterions can include any of the dicationic compounds
previously identified for use in the production of dicationic ionic
liquids. In addition, monoionic counterparts of these may be used. Thus,
for example, quaternary ammonium, protonated tertiary amines,
phosphonium, and arsonium groups are useful as cationic counterions for
dianionic molecules to form dianionic ionic liquids in accordance with
the present invention.

[0224] Similarly, anionic counterions can be selected from any of the
dianionic molecules discussed herein useful in the creation of dianionic
ionic liquids. These would include dicarboxylates, disulphonates, and
disulphates. The corresponding monoionic compounds may also be used
including carboxylates, sulphonates, sulphates and phosphonates. Halogens
may be used as can triflate, NTf2.sup.-, PF6.sup.-,
BF4.sup.- and the like. The counterions should be selected such that
the diionic liquids have good thermal and/or chemical stability and have
a solid/liquid transformation temperature and/or a liquid range as
described herein. Finally, the ionic groups of the present invention can
be substituted or unsubstituted. They may be substituted with halogens,
with alkoxy groups, with aliphatic, aromatic, or cyclic groups, with
nitrogen-containing species, silicon-containing species, with
oxygen-containing species, and with sulphur-containing species. The
degree of substitution and the selection of substituents can influence
the properties of the resulting material as previously described in
discussing the nature of the bridge or chain. Thus, care should be taken
to ensure that excessive steric hindrance and excessive molecular weight
are avoided, that resulting materials does not lose its overall
flexibility and that nothing will interfere with the ionic nature of the
two ionic species.

[0225] The diionic liquids of the present invention can be used in pure or
in substantially pure form as carriers or as solvents. "Substantially" in
this context means no more than about 10% of undesirable impurities. Such
impurities can be either other undesired diionic salts, reaction
by-products, contaminants or the like as the context suggests. In an
intended mixture of two or more DILS, neither would be considered an
impurity. Because they are non-volatile and stable, they can be recovered
and recycled and pose few of the disadvantages of volatile organic
solvents. Because of their stability over a wide liquid range, in some
instances over 400° C., they can be used in chemical synthesis
that require both heating and cooling. Indeed, these solvents may
accommodate all of the multiple reaction steps of certain chemical
syntheses. Of course, these diionic liquids may be used in solvent
systems with cosolvents and gradient solvents and these solvents can
include, without limitation, chiral ionic liquids, chiral non-ionic
liquids, volatile organic solvents, non-volatile organic solvents,
inorganic solvents, water, oils, etc. It is also possible to prepare
solutions, suspensions, emulsions, colloids, gels and dispersions using
the diionic liquids.

[0226] In addition to discrete diionic salts and diionic liquid salts, it
is also possible to produce polymers of these materials. Polymers may
include the diionic salts within the backbone or as pendant groups and
they may be cross-linked or non-cross-linked.

[0227] In addition to being useful as solvents and reaction solvents, the
dianionic liquids of the present invention can be used to perform
separations as, for example, the stationary phase for gas-liquid
chromatography. Dicationic ionic liquid salts, which may be used for
exemplification include: (1) two vinyl imidazolium or pyrrolidinium
dications separated by an alkyl linkage chain (of various length) or (2)
one vinyl imidazolium or pyrrolidinium cation separated an alkyl linkage
chain (of various length) and connected to a methyl, ethyl, propyl, or
buylimidazolium cation or a methyl, ethyl, propyl, or butylpyrrolidinium
cation. See below. Any anionic counterion discussed may be used. Note
that the presence of unsaturated groups facilitates cross-linking and/or
immobilization.

##STR00002##

Dianionic anions can also be used with either monocations or dications to
form a variety of different ionic liquid combinations. When a dication is
used, anyone is used as charge balance must be preserved. The dianionic
anions can be of the dicarboxylic acid type (i.e., succinic acid,
nonanedioic acid, dodecanedioic acid, etc), as shown below.

##STR00003##

Diionic liquid salts can be coated on a capillary (or solid support) and
optionally, subsequently polymerized and/or cross-linked by, for example,
two general methods. In the first method, the ionic liquid are coated via
the static coating method at 40° Celsius using coating solution
concentrations ranging from 0.15-0.45% (w/w) using solutions of methylene
chloride, acetone, ethyl acetate, pentane, chloroform, methanol, or
mixtures thereof. After coating of the ionic liquid is complete, the
column is purged with helium and baked up to 100° Celsius. The
efficiency of naphthalene is then evaluated to examine the coating
efficiency of the monomer ionic liquid stationary phase. If efficiency is
deemed sufficient, the column is then flushed with vapors of
azo-tert-butane, a free radical initiator, at room temperature. After
flushing with the vapors, the column is then fused at both ends and
heated in an oven using a temperature gradient up to 200° Celsius
for 5 hours. The column gradually cooled and then re-opened at both ends,
and purged with helium gas. After purging with helium gas overnight, the
column is then heated and conditioned up to 200° Celsius. After
conditioning, the column efficiency is then examined using naphthalene at
100° Celsius and the stationary phase coated layer examined under
a microscope. Note that the cross-linking process can, and often does,
also cause immobilization. "Immobilized" in the context of the invention
means covalently or ionically bound to a support or to another ionic
liquid (including diionic liquid salts) or both. This is to be compared
with ionic liquids which may be absorbed or adsorbed on a solid support.
Solid support in these particular instances were intended to include
columns.

[0228] It is not necessary, however, to cross-link these materials prior
to their use in GC. They may be adsorbed or absorbed in a column, or
indeed on any solid support. However, at higher temperatures, their
viscosity may decrease and they can, in some instances, flow and collect
as droplets which can change the characteristics of the column.

[0229] Another method involves adding up to 2% of the monomer weight of
2,2'-azobisisobutyronitrile ("AIBN") free radical initiator to the
coating solution of the monomer. The capillary column is then filled with
this solution and coated via the static coating method. After coating,
the capillary column is then sealed at both ends and placed in an oven
and conditioned up to 200° Celsius for 5 hours. The column is
gradually cooled and then re-opened at both ends, and purged with helium
gas. After purging with helium gas overnight, the column is then heated
and conditioned up to 200.° Celsius. After conditioning, the
column efficiency is then examined using naphthalene at 100°
Celsius and the stationary phase coated layer examined under a
microscope.

[0230] In addition to the free radical polymerization of an alkene, other
polymerization reactions involving other functional groups either
attached to the aromatic ring of the cation, the linkage chain connecting
two cations (to form a dication), or the anion can be achieved. Examples
of such reactions may include cationic and anionic chain growth
polymerization reactions, Ziegler-Natta catalytic polymerization, and
step-reaction polymerization. The use of two different monomers to form
copolymers through addition and block copolymerization can also be
achieved. Additionally, condensation polymerization can be used to
connect through functional groups such as amines and alcohols. All
polymerization and cross-linking reactions discussed in the following 2
references can be used: "Comprehensive Polymer Science--The synthesis,
Characterization, Reactions and Applications of Polymers" by Sir Geoffrey
Allen, FRS; "Comprehensive Organic Transformations: a guide to functional
group preparations" by Richard C. Larock. 2nd Edition. Wiley-VCH, New
York. Copyright, 1999. ISBN: 0471190314.

[0233] Note that some of the salts reflected in EXAMPLE A--Tables 1 and 2
may not reflect the correct number of anions; usually 2 (see EXAMPLE
A--Table 3). Note that the names of the compounds found in EXAMPLE A
Tables 1 and 2 are found in EXAMPLE A Table F. Compounds 1, 5, 9, and 13
were synthesized by reacting one molar equivalent of 1,3-dibromopropane;
1,6-dibromohexane; 1,9-dibromononane; and 1,12-dibromododecane,
respectively, with two molar equivalents of 1-methylimidazole at room
temperature. Compound 17 was synthesized by reacting one molar equivalent
of 1,9-dibromononane with two molar equivalents of 1-butylimidazole at
room temperature. Compounds 21 and 24 were synthesized by refluxing one
molar equivalent of 1,3-dibromopropane and 1,9-dibromononane,
respectively, with 1,2-dimethylimidazole dissolved in 125 mL 2-propanol
for 24 hours. Compound 28 was synthesized by refluxing one molar
equivalent of 1,12-dibromododecane with two molar equivalents of
1-benzylimidazole in 100 mL of 2-propanol for 24 hours. Following
complete reaction (as monitored by NMR), the products were all purified
by extraction with ethyl acetate and dried under a P20 sub.5 vacuum.

[0234] Compounds 31 and 34 were produced by refluxing one molar equivalent
amount of 1,3-dibromopropane and 1,9-dibromononane with two equivalents
of 1-methylpyrrolidine in 100 mL of 2-propanol for 24 hours. Compound 37
was synthesized by refluxing two molar equivalents of 1-butylpyrrolidine
with one equivalent of 1,9-dibromononane in 100 mL of 2-propanol for 24
hours. These salts were also extracted with ethyl acetate and dried under
vacuum. All metathesis reactions involving
N-lithiotrifluoromethylsulfonimide, hexafluorophosphoric acid, and sodium
tetrafluoroborate were performed using previously published procedures.
Ionic liquids formed via metathesis reactions were tested with silver
nitrate to ensure no halide impurities remained.

[0236] Surface tension values were measured at room temperature
(23° C.) using a Model 20 DuNuoy Tensiometer (Fisher Scientific,
Fair Lawn, N.J.) equipped with a platinum-iridium ring with a mean
circumference of 5.940 cm and a ring/wire radius of 53.21. The densities
of the ionic liquids or, more correctly, the temperature of solid/liquid
transformation (used synonymously except as indicated otherwise
explicitly or by context) were determined at 23° C. by placing 2.0
mL of the ionic liquid in a 2.0 mL volumetric tube and weighing by
difference. The melting points of the ionic liquids were determined using
a Perkin Elmer Pyris 1 Differential Scanning calorimeter (Boston, Mass.).
Typical methods involved using a 10° C./min temperature ramp to
determine and identify the first and second order thermal transitions.
Melting points could not be easily determined for all compounds. For
solid compounds, the melting points were verified using a capillary
melting point apparatus. Refractive index measurements were conducted at
23° C. using a Bausch & Lomb Abbe-3L refractometer.

[0237] The preparation of the capillary columns for inverse gas-liquid
chromatographic analysis was performed using a previously described
procedure. All capillary columns had efficiencies between 2100 to 2500
plates/meter. Characterization of the capillary columns and probe
molecule descriptions are listed in supplemental information. Multiple
linear regression analysis (MLRA) and statistical calculations were
performed using the program Analyse-it (Microsoft, USA).

[0238] EXAMPLE A Tables 1, 2, and 3 give the structures of the two classes
(39 compounds) of geminal dicationic ionic liquids synthesized and
characterized. Ionic liquids containing imidazolium-based dications with
different alkyl linkage chain lengths connecting the cations and/or
different alkyl substituents on the imidazolium moiety comprise one group
of ionic liquids. In most cases, each geminal dicationic entity was
paired with four different anions (Br.sup.-, NTf2.sup.-,
BF4.sup.-, and PF6.sup.-, EXAMPLE A Table 3).
Pyrrolidinium-based geminal dications with different alkyl linkage chain
lengths connecting the cationic and/or different alkyl substituents on
the pyrroldinium group are also shown in EXAMPLE A Table 3. For each
dication in this class, separate ionic liquids containing three anions
(Br.sup.-, NTf2.sup.-, and PF6.sup.-) were synthesized. EXAMPLE
A Tables 1 and 2 give the physicochemical properties for these
thirty-nine geminal ionic liquids. Surface tension, density, melting
point, and refractive index values were recorded for those samples that
were liquids at room temperature. For samples that were solids at room
temperature, only the melting point was determined. The
miscibility/solubility of all ionic liquids in both heptane and water are
indicated as well.

[0239] Surface Tension. Plots of surface tension data are shown in FIG. 1
for several geminal room temperature ionic liquids. The length of the
alkyl linkage chain separating the dications is observed to have only
small effects on the surface tension. Considering ILs 2, 6, 10, and 14
(EXAMPLE A Tables 1, 2, and/or 3) which all contain the
bis(trifluoromethylsulfonyl)imide (NTf2.sup.-) anion and
3-methylimidazolium cations separated by 3, 6, 9 and 12 carbon linkage
chains, respectively, it is apparent that increasing the length of the
connecting linkage chain slightly decreases the surface tension (˜
2.4 dynes/cm). A similar trend is observed for the ionic liquids
containing other anions (e.g., BF4.sup.-, Br.sup.-, PF6.sup.-).
These results are quite different from those obtained for monocationic
ionic liquids by Law, et al. It was reported that the surface tension for
a series of 1-alkyl-3-methylimidazolium-based ionic liquids containing 4,
8, and 12 carbon alkyl groups in the one position of the imidazole ring
(refer to EXAMPLE A Table 3 for the ring numbering of the imidazolium
cation) significantly decreased with increasing alkyl chain length. The
largest decrease in surface tension was observed between
1-butyl-3-methylimidazolium hexafluorophosphate and
1-dodecyl-3-methylimidazolium hexafluorophosphate in which the total
decrease in surface tension was nearly 20 dynes/cm at 330 K. It was also
proposed that for a fixed cation at a specific temperature, the compound
with the larger anion would possess a higher surface tension. However,
our data indicates that this is not true for the geminal dicationic ionic
liquids, and if anything, is opposite to what was observed previously for
the monocationic-type ionic liquids (EXAMPLE A Tables 1 and 2).

[0240] Diionic liquids 17-20 contain nonpolar butyl groups in the three
position of the imidazolium rings. The surface tension values are
significantly smaller (11%-17%) than those of diionic liquids 9-12 and
13-16 which contain the 3-methylimidazolium dications separated by a
nonane and dodecane linkage chain, respectively. This data seems to
indicate that the alkyl substituent located on the three position of the
imidazolium ring plays a more important role in lowering the surface
tension than the alkyl linkage chain that separates the geminal
dications.

[0241] Replacing hydrogen with a methyl group on the two position of the
imidazolium ring (refer to EXAMPLE A Tables 1, 2, and 3) has little
effect on the surface tension. In the case of diionic liquids 25 and 26
containing the 2,3-dimethylimidazolium geminal dications separated by a
nonane linkage chain with NTf2.sup.- and BF2.sup.- anions,
respectively, the surface tension values are similar to the corresponding
3-methylimidazolium dications (diionic liquids 10 and 11) also containing
the nonane connecting chain. Overall, this data indicates that as the
alkyl chain in the 3-position of the imidazolium ring increases in
length, the surface tension decreases much more drastically than
corresponding increases in the length of the connecting linkage chain.

[0242] Density. As shown in FIG. 2, the densities of the
3-methylimidazolium geminal dicationic ionic liquids were found to be
anion dependent and to decrease with increasing length of the hydrocarbon
linkage chain. While increases in the linkage chain decreases the density
of these ionic liquids, the nature of the anion has a greater influence,
with densities in the order of
NTf231>PF6.sup.->Br>BF4 (EXAMPLE A Tables 1,
2, and FIG. 2). The decrease in density with increasing alkyl chain
length has been reported previously for a large series of
1-alkyl-3-methylimidazolium ionic liquids.

[0243] When the methyl group on the three position of the imidazolium ring
is replaced with a butyl group, the density decreases for all ionic
liquids in the series, regardless of the anion (compare 9-12 to 17-20,
Table 1). However, by replacing the hydrogen at the two position of the
ring with a methyl group, the density does not appear to change (see
10-11 and 25-26, EXAMPLE A Table 1).

[0244] Melting Points. From this study, four main factors were found to
affect the melting points of these geminal-dicationic ionic liquids.
These factors which apply to dianions as well are: (1) the length and
type of the linkage chain or bridge separating the geminal diions, (2)
the nature of the diions (e.g., imidazolium versus pyrrolidinium), (3)
the substituents and their placement on the dianions, and (4) the nature
of the counterion.

[0245] Considering first the 3-methylimidazolium-based dicationic ionic
liquids, longer bridging groups generally result in a lowering of the
melting points. This observation applies to diionic liquids generally. In
all of the above-noted cases except for the geminal dications with
NTf2.sup.- anions, which were all liquids regardless of the linkage
chain used, compounds containing three and six carbon linkage chains were
salts with relatively high melting points. By connecting the
3-methylimidazolium dications with a nonane linkage chain, all samples
were room temperature ionic liquids except for the hexafluorophosphate
salt, which had a melting point of 88° C. When the dications were
connected by a dodecane linkage chain, however, all compounds were room
temperature ionic liquids. Looking more generally at the dianions and
dications that can be used to make diionic liquids in accordance with the
present invention, the chain length between the ionic species should be
longer than the length of a 2 carbon chain, and no longer than a 40
carbon chain. Preferably, chain lengths are equivalent to the length of a
3 to 30 carbon chain. The degree and types of substituents, if any, may
have an effect on length as well, the larger the molecule, generally, the
higher its temperature of solid/liquid transformation. Therefore, any
chain length, any chain content and any chain substitution pattern may be
used, as long as the melting point of the resulting diionic liquid salt
is less than about 400° C., preferably about 100° C. or
less, preferably about 60° C., more preferably about room
temperature or less (25° C.).

[0246] In addition to the effect of the different length and types of
bridges connecting the dications, the anion also played a role in
determining the melting point. In nearly very case of the imidazolium
dications, the melting points increased in the following order:
NTf2.sup.-<BF4.sup.-<PF6.sup.-<Br.sup.- (EXAMPLE
A Tables 1 and 2).

[0247] Other anions which can be used to form dicationic ionic liquids
include, without limitation, trifilates, carboxylates, sulfonates and
sulfates (both mono- and poly-anionic species). Dianionic ionic liquids
can be produced from any dianion which can form a stable salt, preferably
which has a melting point below 400° C., more preferably at or
below 100° C., most preferably at or below room temperature
(25° C.). These include dicarboxylate, disulfonate and disulfates.
Mixed dianions, one made from, for example, a dicarboxylate and a
disulfate, are also desirable. Cations or counterions for these include,
again without limitation, the dications listed in EXAMPLE A Tables 1 and
2, as well as their monocationic counterparts. This is as long as they
can form a stable diionic salt and have a melting point as described
above.

[0248] The substituents and their position on the imidazolium ring also
affected the melting points of these compounds. These same considerations
apply to substituted anions as well. Considering 17-20 which contain the
3-butylimidazolium dications connected by a nonane linkage chain, the
melting points were lowered significantly by replacing the methyl group
(see 9-12) with a butyl group. In the case of 12, which consists of the
3-methylimidazolium dications connected by a nonane linkage chain with
the PF6.sup.- anion, the melting point is decreased by nearly
60° C. by replacing the methyl groups with butyl groups to form
20. In addition, methylation of the 2-positions of the imidazolium
dications significantly increases the melting point of these compounds
(see 21-27, EXAMPLE A Table 1). In the case of 21 which contains the
2,3-dimethylmidazolium dication connected by a propane linkage chain, the
melting point is nearly 135° C. higher than the corresponding
3-methylimidazolium dication also connected by a propane linkage chain
(1). Ngo et al. have previously reported the melting points for
1-ethyl-3-methylimidazolium bromide to be 79° C. whereas the
melting point for 1-ethyl-2,3-dimethylimidazolium bromide was found to be
141° C., a difference of nearly 62° C. While the methyl
group on the two position of the imidazolium ring has little effect on
the surface tension and density of the geminal dicationic ionic liquids,
it is seen to have a profound effect on their melting points, more so for
the dicationic ionic liquids than for the traditional
1-alkyl-3-methylimidazolium ionic liquids.

[0249] Finally, by replacing the 3-methylimidazolium dication with the
3-benzylimidazolium dication (28-30) and connecting them by a dodecane
bridge, the melting points appear higher compared to the
3-methylimidazolium series, especially in the case of the bromide salt.

[0250] In general, the melting points of the pyrroldinium-based geminal
dicationic compounds are significantly higher than their corresponding
imidazolium analogues. Indeed, only two of their NTf2.sup.- salts
can be considered ionic liquids. However, as will be discussed (vide
infra), these particular RTILs may have the greatest thermal stability
and other highly useful and interesting properties.

[0251] The melting points for the pyrrolidinium-based dications show
similar trends to the imidazolium-based salts. In the two cases involving
the propane and nonane linkage chains, the melting point decreases as the
linkage chain becomes longer. However, in contrast to the
imidazolium-based dications, the pyrrolidinium-based dications are still
relatively high melting solids when separated by a nonane alkyl chain.
Additionally, substituting a butyl group instead of a methyl group on the
quaternary amine of the pyrrolidinium cation causes a decrease in the
melting point for the bromide dication but an increase in the melting
point for the dications containing bis(trifluoromethylsulfonyl)imide and
hexafluorophosphate anions.

[0252] From the data in EXAMPLE A Tables 1 and 2, it appears that longer
alkyl linkage chains and long aliphatic substituents on the quaternary
amine produce either low melting salts or room temperature ionic liquids.
Further, the NTf2.sup.- salts have lower melting points than
corresponding salts with other anions. The contributions of the linkage
chain (bridge), and other substituents on the geminal dicationic salts,
to the number of possible conformational states (and possibly crystal
polymorphs) will be considered in the crystal structure section of this
paper.

[0253] Solubility. The solubility behavior of all thirty-nine geminal
dicationic ionic liquids in water and heptane also was explored. None of
the dicationic ionic liquids were soluble in heptane. However, most of
the ionic liquids containing bromide and tetrafluoroborate anions were
soluble in water. Nevertheless, for the tetrafluoroborate ionic liquids,
it was found that by using a long linkage chain and a more hydrophobic
alkyl substituent on the three position of the imidazole ring (see
compounds 15 and 19), the solubility of the salt in water decreases. In
general, the solubility behavior of the geminal dicationic ionic liquids
in both water and heptane was quite similar to the monocationic ionic
liquids with NTf2.sup.- and PF6.sup.- salts being immiscible
with water and Br.sup.- and BF4.sup.- salts being miscible with
water. Indeed, the monoionic counterparts of the diionic liquid salts of
the present invention are a good predicator of the solubility of a
diionic liquid salt.

[0254] In the case of the dicationic ionic liquid 28 which consists of the
3-benzylimidazolium dication separated by a dodecane linkage chain and
bromide anion, the hydrophobicity of the dication evidently overrides the
coordinating nature of the bromide anion to make this particular ionic
liquid insoluble in water. This is a good example that the properties of
the individual cations and anions can be balanced and changed in order to
produce ionic liquids (or solids) with the desired properties and
characteristics.

[0255] Thermal Stability. The thermal stabilities of the geminal
dicationic ionic liquids were found to be significantly higher than what
has been observed for many traditional imidazolium-based ionic liquids.
Thermal stabilities were measured by immobilizing an approximate
0.15-0.20 microns film of the ionic liquid on the inner wall of a fused
silica capillary. The capillary was then heated slowly in an oven and a
very sensitive flame ionization detector (or mass spectrometer) used to
detect any volatilization or decomposition of the ionic liquid. There are
several advantages of using this set-up to measure the thermal
stabilities of ionic liquids. The thermal stability is measured in the
absence of oxygen by purging the capillary with a continuous flow of an
inert gas such as helium, hydrogen, or nitrogen. In addition, the
detection limit of the detector is very low (˜10 ppm to 10 ppb,
depending on the compound) allowing for very sensitive detection of any
thermally induced decomposition/volatilization products from the ionic
liquid. Finally, this approach can use mass spectrometry detection to
determine the likely volatilization/decomposition products.

[0256] FIG. 3 shows a thermal stability diagram containing three
traditional ionic liquids and four dicationic ionic liquids. The
traditional ionic liquids have thermal stabilities ranging from
145° C. (1-butyl-3-methylimidazolium chloride) to 185° C.
(1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide). However,
the thermal stabilities of the geminal dicationic ionic liquids are
observed to range from 330° C. to 400° C., depending on the
cation used. The highest thermal stability (>400° C.) was
obtained with the C9(mpy2-NTf2 (35) ionic liquid
(1-methylpyrrolidinium dication separated by a nonane linkage chain)
while the lowest volatilization/decomposition temperature (330°
C.) was observed for the C9(bpy)2-NTf2 (38,
1-butylpyrrolidinium dication separated by a nonane linkage chain) ionic
liquid. The maximum thermal stabilities of C9(mim)2-NTf2
(10, 1-methylimidazolium dication) and C12(benzim)2-NTf2
(29, 3-benzylimidazolium dication separated by a dodecane linkage chain)
were observed to be nearly identical (350-360° C.). In most cases,
slight to moderate decomposition/volatilization of the dicationic ionic
liquids were observed at these high temperatures. However, due to
charring of the polyimide coating on the outside of the fused silica
capillary tubing at these high temperatures, the ionic liquids were only
tested up to 400° C.

[0257] While the physical and thermal properties of the dicationic ionic
liquids are quite impressive, another interesting fact is that some of
these compounds possess useful liquid ranges in excess of 400° C.
and one of these (C9(mpy)2-NTf2) 35 has a stable liquid
range of ˜ -4° C. to >400° C. This property will
undoubtedly ensure their use for a wide variety of applications in which
this large liquid range and high thermal stability can be exploited. In
accordance with one aspect of the present invention, the ionic liquids of
the present invention, which are salts of a dianion or dication, are
stable. Stability in the context of the present invention means that they
will neither substantially decompose nor volatilize at a temperature of
under about 200° C. when measured by inverse gas chromatography as
described herein. More preferably, the stable ionic liquids of the
present invention which are dianionic or dicationic salts, are stable in
that they will not substantially decompose or volatilize at a temperature
of under about 300° C.

[0258] In FIG. 3, it is believed that the detector response shown for
compounds D, E and F, between approximately 200 and approximately
300° C. are from impurities and not from the compounds tested.
Still, less than 10% of the weight of the material tested decomposes or
volatilizes when exposed to 200° C. or in preferred embodiments,
300° C., for an hour, they can be said to be stable in accordance
with the present invention.

[0259] In particularly preferred embodiments in accordance with the
present invention, dianionic or dicationic ionic liquid salts are
provided, which are stable in that they will neither substantially
decompose nor substantially volatilize at a temperature of under
200° C. and will have a temperature of solid/liquid transformation
of 400° C. or less. More preferably will have a temperature of
solid/liquid transformation of 100° C. or less, most preferably
will have a temperature of solid/liquid transformation of 25° C.
or less.

[0260] As mentioned previously, the diionic liquids (salts of dianions and
dications as described herein) have an important use because of their
stability at wide ranges of temperature and unique liquid properties.
Many of these liquids have unexpectedly low temperatures of solid-liquid
transformation, which from a fundamental standpoint depends upon the
energy of their crystal lattice. There are well-known and rather crucial
barriers to precisely calculating these energies, i.e., the true
determination of atom-atom potentials. On the other hand, the accurate
measurement (required for comparison) of solid-liquid transformation
temperatures for this family of ionic compounds also have difficulties.
The transformation is not sharp in time and the peaks on DSC curves
become very broad. Formally speaking, the temperature of this
transformation can be very different from the true melting point which is
the temperature of thermodynamic equilibrium between solid and liquid
states.

[0261] Solvation Characteristics. We have previously reported that the
Abraham solvation model, a linear free energy approach that utilizes
inverse gas-liquid chromatography to describe the solvation properties of
a liquid, can be used to characterize room temperature ionic liquids.
Described by equation 1, the model provides the so-called "interaction
parameters" (r, s, a, b, l) by using multiple linear regression analysis
to fit the retention factor (k, determined chromatographically) to the
solute descriptors (R2, π2Hα2H,
β2H, log L16) for a wide variety of probe solute
molecules.

log k=c+rR2+sπ2H+bβ2H+1 log L16
[1]

[0262] The solvation properties of four dicationic ionic liquids (see
EXAMPLE A Table 4) were evaluated and the interaction parameters compared
to those obtained for their traditional monocationic analogues
1-butyl-3-methylimidazolium and 1-butyl-1-methylpyrrolidinium ionic
liquids.

[0263] Nearly all interaction parameters of the dicationic ionic liquids
C4(mim)2-NTf2 and C9(mim)2-NTf2 (10) are
similar to the corresponding monomer-type ionic liquids,
1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. This is
also observed for the pyrrolidinium dication,
C9(mpy)2-NTf2 (35), as it differs from the monomer-type
analogue (1-butyl-1-methylpyrrolidinium
bis(trifluoromethylsulfonyl)imide). This indicates that the well-known
and highly useful solvation properties of traditional RTILs are very
similar to those of the geminal dicationic RTILs. The only interaction
parameter that is statistically different between the three ionic liquids
is the "r" interaction parameter, namely the ability of the ionic liquid
to undergo.π-π and n-π interactions with probe solute molecules.
Because the pyrroldinium cation is not aromatic, the higher r values may
be due to the anion as each anion contains two sulfone groups that are
capable of undergoing such interactions. However, this was not observed
for the traditional ionic liquids evaluated previously in our study.

[0264] Finally, the interaction parameters for the 3-benzylimidazolium
geminal dication separated by a dodecane linkage chain with the
NTf2.sup.- anion (29) appear similar to those observed previously
for 1-benzyl-3-alkyl-imidazolium ionic liquids. However, the hydrogen
bond acidity term, b, is larger for the geminal dicationic ionic liquid.
This may be due to the increased acidity of the proton at the 2-position
of the imidazolium ring induced by the electron withdrawing benzyl group.

[0265] As noted earlier, the viscosity of some diionic salts decreases
sharply with increasing temperature. Consequently at high temperatures,
previously uniform coated capillaries, particularly ones that are
prepared by adsorption or absorption, rather than immobilization, can
experience film disruption (due to flow, etc.). When a uniformly coated
GC capillary, for example, slowly changes to a nonuniformly coated
entity, the analyte retention times and efficiency tend to decrease.

[0266] To overcome these issues, where necessary, and in accordance with
another aspect of the present invention, there is provided a process
which includes the free radical reaction of ionic liquid monomers to
provide a more durable and robust stationary phase, as well as the
cross-linked and/or immobilized stationary phases and the columns that
include same. By partially cros slinking the ionic liquid stationary
phase using a small percentage of free radical initiator, high efficiency
capillary columns are produced that are able to endure high temperatures
with little column bleed. It was found that low to moderate temperature
separations (30° C.-280° C.) can be carried out with high
selectivity and efficiency using special partially cross-linked ionic
liquid stationary phase mixtures. These stationary phases retain their
"gelatinous," "semi liquid," amorphous state. For separations conducted
at higher temperatures (300° C.-400° C.), more highly
cross-linked/immobilized stationary phases are well-suited to provide
high selectivity and efficient separations with low column bleed. The
effect of different functionalized ionic liquid salt mixtures and
initiator concentrations is studied for these two types of stationary
phases. The accomplished goal is to maximize their separation efficiency,
thermal stability, and column lifetime, without sacrificing the unique
selectivity of the stationary phase.

[0267] The following materials were used to illustrate the unique
advantages of cross-linked stationary phases comprising diionic liquid
salts in accordance with the present invention: 1-vinylimidazole,
1-bromohexane, 1-bromononane, 1-bromododecane, 1,9-dibromononane,
1,12-dibromododeeane, 1-bromo-6-chlorohexane, 1-methylimidazole,
N-Lithiotrifluoromethanesulfonimide, 2,2'-Azobisisobutyronitrile (AIBN),
dichloromethane, ethyl acetate, and all test solutes were purchased from
Aldrich (Milwaukee, Wis.). Untreated fused silica capillary tubing
(0.25-mm inner diameter) and a fatty acid methyl ester (FAME) kit
containing 19 standards was purchased from Supelco (Bellafonte, Pa.).
Structures and physico-chemical properties of the monocation monomers and
the dication crosslinkers used are shown in EXAMPLE A Table A. Monomers
1, 2, and 3 were synthesized by reacting one molar equivalent of
1-vinylimidazole with a slight molar excess of 1-bromohexane,
1-bromononane, and 1-bromododecane, respectively. These reactions were
performed at room temperature in round bottom flasks lined with aluminum
foil to prevent thermal/photo-induced polymerization. Care should be
taken when synthesizing and purifying these compounds to minimize excess
heat/light during reaction or roto-evaporation to prevent unwanted
reaction of the ionic liquid. The resulting bromide salt was evaporated
under vacuum to remove the excess 1-bromoalkane. Three 15 mL aliquots of
ethyl acetate were used to wash the ionic liquid to remove any other
impurities. After evaporating the ethyl acetate under vacuum, the bromide
salt was dissolved in water and mixed with one molar equivalent of
N-Lithiotrifluoromethanesulfonimide, also dissolved in water. After
stirring for 12 hours, the water was removed and the remaining ionic
liquid thoroughly washed with water using three 50 mL aliquots of water.
A portion of the third aliquot of water was subjected to the silver
nitrate test to ensure the absence of silver bromide precipitate. The
monomers were then dried under vacuum and then placed under a
P2O5 vacuum in the absence of light.

[0268] The dication crosslinkers were synthesized using a modified
procedure recently reported for a series of geminal dicationic ionic
liquids. Compound 4 in Table A is a mixture of C6(vim)22+
(m/z=272.1), C6vm(im)22+ (m/z=260.1), and
C6(mim)22+ (m/z=248.1) in a 1:2:1 molar mixture,
respectively, as indicated in the electrospray mass spectrum in FIG. 4.
When acquired in positive ion mode, the most dominant ions for these
three structurally similar compounds appear to be the +1 ion minus a
proton. Further experiments conducted in our group in which the C-2
proton on the imidazolium ring (see FIG. 4 for numbering of ring system)
is deuterated indicates that this proton is lost and causes one of the
positive charged aromatic rings to neutralize charge and give rise to the
+1 ion (data not shown). This mixture was synthesized by reacting one
molar equivalent of 1-bromo-6-chlorohexane with one molar equivalent of
1-methylimidazole in an ice bath overnight. Subsequently, one molar
equivalent of 1-vinylimidazole was added dropwise over a period of 30
minutes and the temperature of the mixture increased to 55° C. for
3 hours. Three 15 mL aliquots of ethyl acetate were used to extract any
excess starting material and the bromide anion was exchanged for the
bis[(trifluoromethane)sulfonyl]imide (NTf2.sup.-) anion by reaction
of two equivalents of N-Lithiotrifluoromethanesulfonimide dissolved in
water for every one equivalent of the crosslinker salt.

[0269] In an analogous manner, the remaining crosslinkers 5, 6, 7, and 8
were prepared by reacting one molar equivalent of the dibromoalkane with
two molar equivalents of 1-vinylimidazole. Compound 9 was prepared by
reacting one molar equivalent of 1-methylimidazole with molar equivalent
of 1-bromononane at 100° C. for 5 hours. Clean-up and metathesis
exchange for the NTf2.sup.- anion was performed as described above
for the synthesis of the monomer ionic liquids.

[0270] Capillaries were coated using the static coating method at
40° C. Coating solutions of the monomer and/or crosslinker ionic
liquids were prepared at concentrations of 0.20% (w/v) in
dichloromethane. Prior to adding the dichloromethane to the monomer
and/or crosslinker mixture, 0.7 mg of AIBN (˜ 3.5% by weight) was
added. AIBN is known to undergo decomposition to form cyanoisopropyl
radicals which subsequently produce several products by dimerization,
disproportionation reactions, or chain reactions. The thermal
decomposition kinetics of AIBN have been well studied using a variety of
spectroscopic and polarographic techniques. Based on an Arrhenius plot,
Van Hook and co-workers have proposed a rate expression for the
decomposition of AIBN in solution to be: kd=1.58×0.1015
exp(-30.8 kcal./RT). For a temperature of 40° C. in which the
capillaries are coated with the initiator present in the coating
solution, this yields a decomposition rate constant of ˜
5.07×10-7 sec-1. Due to the fact that this rate constant
is so small and that the coating rate is relatively fast, there should be
very little polymerization of the monomer/crosslinker mixture during the
coating of the capillary.

[0271] After coating, the ends of the capillary were flame sealed and the
capillary placed in a GC oven and heated from 40° C.-80° C.
at 1° C./min. The capillary was then held at 80° C. for 5
hours to ensure complete polymerization. Helium carrier gas was then
flushed through the capillary at a rate of 1 mL/min and the capillary
conditioned from 30° C. to 120° C. at 3° C./min and
held at 120° C. for two hours.

[0272] Solvation thermodynamics can be determined chromatographically by
recognizing that the Gibbs free energy change, .ΔG°, of a
solute between the mobile phase and the stationary phase can be described
by equation 1:

Δ G ° = - RT ln ( k Φ
) [ 1 ] ##EQU00001##

where k is the solute retention factor and φ is the column phase
ratio. An expression shown in equation 2 can then be derived and
illustrates the dependence of enthalpy, ΔH°, and entropy,
ΔS°, on the change of the retention factor with temperature:

ln k = - ( Δ H ° R )
1 T + [ Δ S ° R + ln Φ ]
[ 2 ] ##EQU00002##

A van't Hoff plot of in k versus 1/T provides the entropy (intercept) and
enthalpy (slope) and describes a solute's transfer from the gas phase to
the ionic liquid stationary phase. In this work, the solvation
thermodynamics were determined for seven different probe molecules,
listed in EXAMPLE A Table D, on two cross-linked ionic liquid phases and
one ionic liquid stationary phase. As EXAMPLE A Table D illustrates, the
probe molecules evaluated in this study differ in terms of size and the
types of functional groups that they possess. For each probe molecule on
each stationary phase, three separate van't Hoff plots were constructed
so that changes in the probe molecule retention factor could be used to
provide an error for each thermodynamic parameter. The probe molecule
retention factors were determined at six different temperatures to obtain
the highest possible correlation coefficient (>0.989).

[0273] Previously we characterized a large number of room temperature
ionic liquids in terms of multiple solvation interactions using the
solvation parameter model, shown in equation

log k=c+rR2+sπ2H+αα2H+bβ.su-
b.2H+l log L16 [3]

This approach utilizes inverse gas-liquid chromatography and allows the
use of a large number of probe molecules to deconvolute solute retention
in terms of the type and magnitude of individual solvation interactions.
The solute descriptors (R2, π2H,
α2H,.β2H, log L16) from Equation 3
are obtained from the literature for many probe molecules containing a
variety of functional groups. The retention factor is determined
chromatographically. The solute descriptors and retention factors are
subjected to multiple linear regression analysis to obtain the
interaction parameter coefficients (r, s, a, b, 1), which ultimately
characterize the stationary phase: r is the ability of the diionic liquid
containing-stationary phase to interact with .π0 and n electrons of
the solute, s is a measure of the dipolarity/polarizability of the
diionic liquid containing-stationary phase, a defines the diionic liquid
containing-stationary phase hydrogen bond basicity, b is a measure of the
hydrogen bond acidity, and 1 refers to the ability of the diionic liquid
containing-stationary phase to separate adjacent members of a homologous
series.

[0274] Test solutes used to determine interaction parameters and solvation
thermodynamics were dissolved in dichloromethane. A Hewlett-Packard model
5890 gas chromatograph and a Hewlett-Packard 6890 series integrator were
used for all separations. Split injection and flame ionization detection
were utilized with injection and detection temperatures of 250° C.
Helium was used as the carrier gas with a column inlet pressure of 3.1
psi and flow rate of 1.0 mL/min. Methane was used to determine the dead
volume of the column. Multiple linear regression analysis and statistical
calculations were performed using the program Analyze-it (Microsoft).

[0275] Equation 4 can be used to approximate the stationary phase film
thickness for gas chromatographic capillaries coated by the static
coating method,

d f = d c × c 400 [ 4 ] ##EQU00003##

where: df is the film thickness of the ionic liquid stationary phase
in micrometers, dc is the diameter of the capillary (in
micrometers), and c is the percentage by weight concentration of the
stationary phase dissolved in an appropriate solvent. FIG. 5 shows the
effect of 1-hexyl-3-vinylimidazolium
bis[(trifluoromethane)sulfonyl]imidate film thickness on the peak
efficiency of naphthalene at 100° C. As the plot clearly
demonstrates, the highest efficiency separations were carried out with a
film thickness of ˜0.07 μm (0.10% w/v of ionic liquid in
dichloromethane) while the worst efficiency separations were obtained on
columns with a film thickness of ˜0.21 μm (0.33% w/v). In this
work, all capillaries were coated with a 0.20% (w/v) coating solution
yielding a film thickness of approximately 0.125 μm.

[0276] Using the ionic liquids in EXAMPLE A Table A, a variety of free
radical cross-linking experiments were carried out in chloroform
following the method of Muldoon and co-workers48 to determine which
ratios of monocationic/crosslinker monomers result in copolymers that
possess the ideal properties for a GC stationary phase. For example, some
copolymers (i.e., formed from monomers 1 and 5) containing only a few
percent by weight crosslinker resemble gum-like polysiloxane phases.
However, other highly cross-linked copolymers formed hard plastics and
are therefore undesirable for gas-liquid chromatographic separations.

[0277] Monocationic monomer ionic liquids 1, 2, and 3 contain the
1-vinylimidazolium cation with hexyl, nonyl, and dodecyl alkyl chains,
respectively. When polymerized, these ionic liquids form linear polymer
chains, as demonstrated previously by Marcilla and co-workers. As
illustrated in Table B, these stationary phases exhibited a range of
initial separation efficiencies, ranging from 2813 plates/meter for ionic
liquid 1 and ˜1900 plates/meter for ionic liquid 3 when conditioned
to 120° C. While it appears that the hexyl substituted
vinylimidazolium cation produces a more efficient stationary phase
coating, subsequent evaluation of the stationary phases using higher
conditioning temperatures revealed that the efficiencies of these
capillaries decrease rapidly. After conditioning up to 350° C.,
volatilization of the ionic liquids resulted in efficiencies that dropped
to several hundred plates/meter. No retention of naphthalene was observed
after conditioning the capillaries to 380° C., indicating an
insufficient amount of ionic liquid remained on the capillary wall.

[0278] To produce a more thermally robust ionic liquid matrix, geminal
dicationic vinylimidazolium crosslinkers with different length alkyl
chains separating the dications were mixed with the monocationic
monomers. These mixtures are shown in Table B under the heading
"partially/fully crosslinked matrices." From our previous solution-based
polymerization experiments, it was found that the concentration of
crosslinker is crucial for the formation of a matrix exhibiting ideal
stationary phase properties (data not shown). Compound 4 (see EXAMPLE A
Table A), is a mixture of three dicationic ionic liquids separated by a
six carbon linkage chain. Electrospray mass spectrometry indicated that
for every one of the 1,6-di(3-methylimidazolium)hexane
[C6(mim)22+] dications and
1.6-di(3-vinylimidazolium)hexane [C6(vim)22+] dications,
there are two of the
1-(3-vinylimidazolium)-6-(3'-methylimidazolium)hexane
[C6vm(im)22+] dications. When a column was prepared by
polymerizing/immobilization only this mixture, the initial efficiency
after conditioning to 120° C. was nearly 3000 plates/meter
(EXAMPLE A Table B). Moreover, the efficiency dropped much less after
conditioning the capillary at higher temperatures. For example, the
efficiency of 4 after conditioning at 350° C. was 1365
plates/meter whereas the efficiencies of the monocationic ionic liquids
without crosslinker ranged from 120 to 197 plates/meter after the same
conditioning step. Clearly, by crosslinking the ionic liquids, the
efficiency and thermal stability of the stationary phase is preserved at
higher temperatures.

[0279] A series of different crosslinked ILs were also synthesized using
various ratios of 1-vinyl-3-hexylimidazolium
bis[(trifluoromethane)sulfonyl]imidate (1) and the dication mixture 4,
described above. The highest efficiencies were obtained with crosslinking
mixtures formed with equal percentages of the monocationic and
crosslinking monomers whereas copolymers formed with a higher
concentration of crosslinker exhibited lower efficiencies (see EXAMPLE A
Table B). The effect of the alkyl side chain of the monocationic monomer
was investigated by preparing equal molar ratios of the crosslinking
mixture 4 with two other monocationic monomers,
1-vinyl-3-nonylimidazolium bis[(trifluoromethane)sulfonyl]imidate (2) and
1-vinyl-3-dodecylimidazolium bis[(trifluoromethane)sulfonyl]imidate (3).
As Table B illustrates, there is very little difference between these
different composition crosslinked matrices in terms of separation
efficiency and loss of efficiency at high temperatures. Recall that
previously it was noted that when the monocationic monomers were
polymerized without crosslinker, the length of the alkyl group appeared
to have an effect on the separation efficiency/thermal stability of the
stationary phase at higher temperatures. This demonstrates that the
length of the alkyl group on the monocationic monomer plays less of a
role in the loss of separation efficiency at high temperatures when it is
part of a crosslinked stationary phase.

[0280] Ionic liquid stationary phases based only on crosslinking monomers
were also evaluated. As shown in EXAMPLE A Table B, one mixture was based
on the crosslinking of vinylimidazolium dications separated by a nonane
linkage chain (0.20% 5) while the second mixture consisted of ionic
liquids 5, 6, 7, and 8, namely dicationic ionic liquid monomers separated
by a nonane, decane, undecane, and dodecane linkage chain, respectively.
This mixture of four crosslinkers, abbreviated as
C9-12(vim)2-NTf2 in EXAMPLE A Table 4, was made due to the
fact that compounds 6 and 8 are supercooled solids at room temperature
and, therefore, are not ideal monomers for creating "gummy" or "waxy"
stationary phases. This mixture consists of 10.88% by weight of 5, 9.29%
of 6, 19.59% of 7, and 60.24% of 8.

[0281] A couple of interesting trends were observed for the highly
crosslinked ionic liquid stationary phases that were not observed for the
monocationic linear or partially crosslinked materials. First, although
the separation efficiency of the completely crosslinked stationary phases
was low after conditioning to 380° C., the ionic liquid stationary
phase was still present as a thin film in the capillary when viewed under
microscope after prolonged exposure to this temperature. In contrast,
only a few partially crosslinked stationary phases (see EXAMPLE A Table
B) provided retention of naphthalene after high temperature conditioning.
All stationary phases formed using monocationic monomers alone appeared
to have decomposed and/or volatilized completely from the capillary wall
after conditioning to 380° C.

[0282] The most impressive and interesting characteristic of the
completely crosslinked ionic liquid stationary phases is their apparent
ability to exhibit a substantial increase in efficiency after
conditioning at high temperatures. Examples of this arc found in EXAMPLE
A Table B under the heading "Crosslinked Ionic Liquid Matrix." In one
such example, a crosslinked matrix previously described containing a
mixture of four dicationic crosslinkers, C9-12(vim)2-NTf2
was formed and the efficiency of this stationary phase was observed to
undergo a 200%-250% increase in efficiency when the column was
conditioned from 300° C. to 350° C. (see EXAMPLE A Table
B). This trend was observed on all highly crosslinked stationary phases
examined and appears to be independent of the initial AIBN concentration
in the coating solution (see EXAMPLE A Table C).

[0283] The fact that the efficiencies of the highly crosslinked stationary
phases increase in this narrow temperature range is not well understood,
but certainly makes them very useful for high temperature separations.
Clearly, by exhibiting this behavior, these stationary phases appear to
exhibit the smallest decrease in efficiency up to temperatures around
350° C. For low to moderate temperature separations (25° C.
to 285° C.), the partially crosslinked stationary phases,
particularly those containing equal weight percentages of ionic liquids 2
and 5, provide the highest efficiency separations up to 285° C.
with little column bleed at temperatures at and above 250° C.
Meanwhile, the completely crosslinked stationary phases provides the
highest efficiency separations with little column bleed up to
temperatures around 300° C.-380° C. Therefore, these two
optimized types of immobilized ionic liquid stationary phases are
specifically proposed for normal GC temperature ranges and higher GC
temperatures, respectively. Low to moderate temperature separations are
optimal with partial crosslinking of the stationary phase whereas high
temperature separations require more extensive crosslinking to maintain
acceptable efficiency and low column bleed.

[0284] The two optimized crosslinked stationary phases chosen for the
moderate (0.10% 2 and 0.10% 5) and high temperature (0.20%
C9-12(vim)2-NTf2) separations, were further studied to
determine the effect of AIBN initiator concentration on their separation
efficiency and thermal stability. As shown in Table B, each copolymer was
formed using a different concentration of AIBN in the coating solution.
These concentrations ranged from 10.0% (w/w of AIBN to ionic liquid) to
0.5%. For the partially crosslinked stationary phase, a higher weight
percentage of initiator results in a slightly more efficient stationary
phase (i.e., 3296 plates/meter for 0.5% AIBN to 3817 plates/meter for
10.0% AIBN). In addition, the efficiencies of the 7.0% and 10.0% by
weight initiator copolymers decrease less rapidly at higher temperatures
(>250° C.) compared to those ionic liquid matrices produced
with lower initiator concentrations. After the stationary phase is
subjected to a temperature ramp up to 385° C., only the two
copolymers formed with 7.0% and 10.0% initiator provide retention of
naphthalene, however with very low efficiency. The other two crosslinked
stationary phases were no longer observed in the capillary after high
temperature conditioning (385° C.) and therefore provided no
retention.

[0285] In the case of the highly crosslinked stationary phase (0.20%
C9-12(vim)2-NTf2), a nearly opposite trend to that
observed for the partially crosslinked ionic liquids was observed
(EXAMPLE A Table B). The efficiencies of the columns after the first
conditioning step are higher for the copolymers formed with lower AIBN
concentration. However, it was still found that a higher weight
percentage of AIBN results in a smaller decrease of efficiency at higher
temperatures compared to the copolymers formed with lower percentages of
AIBN. All of the highly crosslinked stationary phases were found to
retain naphthalene after conditioning at 385° C. As discussed
previously, the highly crosslinked stationary phases exhibit an increase
in the separation efficiency for naphthalene after being conditioned to
350° C. as compared to being conditioned at only 300° C.
The magnitude of this increase does not appear to be directly related to
the initiator concentration. For example, the efficiency increase
exhibited by the copolymer formed with 3.5% AIBN is ˜171% higher
after the 350° C. program compared to the 300° C. program
whereas that for the 10% AIBN is ˜250% higher. As previously
observed for the partially crosslinked ionic liquids, the overall
decrease in efficiency is lowest for copolymers formed with higher AIBN
concentrations.

[0286] This indicates that at high temperatures the most efficient
stationary phases appear to be those that are crosslinked with a weight
percentage of AIBN greater than 7.0%. In contrast, for lower/normal
temperature separations, the choice of the monocationic monomer and
crosslinker plays a more important role in the stationary phase
efficiency and higher initiator concentration tends to prevent large
decreases in efficiency with increasing temperature (see Table B).

[0287] It has been demonstrated previously that room temperature ionic
liquids act as broadly applicable, superb gas chromatographic stationary
phases in that they exhibit a dual nature retention behavior.
Consequently, ionic liquid stationary phases have been shown to separate,
with high efficiency, both polar and nonpolar molecules on a single
column. By producing stationary phases that are either partially or
highly crosslinked, it is of interest to ensure that the solvation
thermodynamics and solvation interactions inherent to ionic liquids are
still retained by their immobilized analogues.

[0288] The thermodynamics (Table D) and solvation interactions (EXAMPLE A
Table E) for the two optimized crosslinked and a neat ionic liquid were
determined as previously described in the Experimental Section. As can be
seen from the data in these tables, both the free energy of transfer of
solute and particularly their interaction parameters are similar for both
the crosslinked and neat monomeric ionic liquid stationary phases. While
the enthalpies of solvation for all probe molecules differed only
slightly between the three ionic liquids, a larger difference was
observed for the entropies of solvation on the highly crosslinked
stationary phase for certain solutes, i.e., 2-chloroaniline, ethyl phenyl
ether, and decane. The entropies of solvation were somewhat more negative
for these molecules indicating that they are part of a more ordered
environment with the highly crosslinked stationary phase. These results
also indicate that solvation by these three ionic liquid-based stationary
phases has a substantial entropic component that contributes to large
differences in solute free energy of transfer (see values for
2-chloroaniline and decane in EXAMPLE A Table D).

[0289] The solvation interaction parameters given in EXAMPLE A Table E
indicate that the neat and two crosslinked ionic liquids are very similar
in terms of selectivity. All three stationary phases interact weakly via
nonbonding and π-electrons (r-term). The hydrogen bond basicity (a)
and dispersion forces (l) were the same within experimental error for all
three stationary phases. The partially crosslinked and neat ionic liquids
possessed the same magnitude of dipolar interactions which were somewhat
lower than those exhibited by the highly crosslinked ionic liquid (see
EXAMPLE A Table E). Within experimental error, all three ionic liquids
possessed the same ability to undergo hydrogen bond acidity (b)
interactions.

[0290] The unique selectivity of ionic liquid stationary phases in the
separation of a wide variety of analyte molecules including alcohols,
alkanes, polycyclic aromatic hydrocarbons (PAHs), polychlorinated
biphenyls (PCBs), and chlorinated pesticides have been demonstrated. The
fact that the selectivity of the ionic liquid stationary phases is
preserved after crosslinking the matrix is demonstrated in FIG. 6 and
FIG. 7. FIG. 6 shows a separation of 19 fatty acid methyl esters (FAMEs)
on a 15 meter column coated with a partially crosslinked IL stationary
phase. This separation is performed in 12 minutes using the temperature
ramp described. FIG. 7 illustrates the separation of a mixture of PAHs
and chlorinated pesticides on a 12 meter highly crosslinked stationary
phase. The 9 minute, high temperature GC separation is carried out using
a temperature program up to 335° C. with little observed column
bleed. While the selectivity of these ionic liquids is little different
from that observed previously with the neat ionic liquids, the fact that
separations can now be accomplished at higher temperatures with little
column bleed, high efficiency, and little shifting of the retention time
after exposure to extreme temperatures further demonstrates the
effectiveness of the immobilized ionic liquid.

[0291] This work addresses the fundamental issues relating to the use of
ionic liquid stationary phases at high temperatures and column
ruggedness. Specifically, it was demonstrated that by employing ionic
liquid monocationic monomers and dicationic crosslinkers, an immobilized
GC stationary phase can be developed. The cross-linked stationary phases
retain the dual nature selectivity behavior inherent to all ionic liquid
stationary phases. In addition, the columns can be used at high
temperatures with low column bleed while simultaneously providing high
efficiency separations. Two types of stationary phases were identified in
this work and differ in terms of their maximum/minimum operating
temperatures. Partially crosslinked stationary phases are best for
separations conducted at temperatures from ambient to 280° C.
while a mostly crosslinked stationary phase is best suited for
temperatures over 300° C. While the moderate to high temperature
range of the mostly crosslinked stationary phase may overlap with the
partially crosslinked matrix, lower efficiency separations were observed
with the mostly crosslinked stationary phase at low temperatures.
Moreover, a dramatic increase in efficiency of the mostly crosslinked
stationary phase at high temperatures further adds to its effectiveness
and usefulness for a variety of applications in high temperature gas
chromatography studies.

[0292] Of course, ionic liquids and in particular the diionic liquid salts
of the present invention can be used in other separation and analytical
techniques. Their range of applicability is in no way limited to
chromatography. One technique in which these materials can be used in
Solid Phase Extraction ("SPE"). In SPE, a sample contains an impurity or
some other element to be separated, identified and/or quantified. This
sample can be placed into a container in which diionic liquid salts of
the present invention can be present in, and more broadly, ionic liquids
in an immobilized form. Ionic liquid materials can be bound (immobilized)
to the walls of the container, adsorbed, absorbed onto a bead or other
structure so as to form a bead or other structure which may rest at the
bottom of the container or be packed throughout the container much as a
liquid chromatography column can be packed with stationary phase.
Alternatively, the ionic liquids and in particular diionic liquid salts
of the present invention can be immobilized by cross-linking or an
analogous immobilization reaction as described herein on some sort of
other solid support such as a bead used in chromatography. These beads
can also be placed at the bottom of, or can fill a container, much as a
packed column used for liquid chromatography. Of course, the solid
support can be any structure placed any where within the container.

[0293] In a particularly preferred embodiment, the container is actually a
syringe where the ionic liquid and/or diionic liquid salts are affixed or
disposed in one fashion or another at the base of the syringe, much as a
filter. When the needle of the syringe is placed in a sample and the
plunger is withdrawn, vacuum is formed drawing sample up into the barrel
of the syringe. This material would pass through at least one layer of
ionic liquid and, in particular, diionic liquid salts in accordance with
the present invention, which would bind at least one of the components of
the liquid. The sample liquid could then be spilled out or the plunger
depressed to eject it, the latter forcing the sample back through the
ionic liquid or diionic liquid salts positioned at the bottom of the
barrel.

[0294] The liquid can be analyzed either for the presence of certain
materials or the absence of the material retained by the ionic liquid or
diionic liquid salts of the present invention. Alternatively, the
retained materials can be removed (such as by placing the materials in a
different solvent) or not and analyzed analytically by other means. The
same technique may be used in a preparative fashion and/or as a means of
bulk purification as well.

[0295] Another technique in which immobilized ionic liquids and diionic
liquid salts of the present invention may be used is solid phase
microextraction or SPME. Broadly speaking, in these techniques, a
separation material (in this case an ionic liquid or in particular a
diionic liquid salt in accordance with the present invention) is
absorbed, adsorbed or immobilized in one way or another on a fiber
generally attached to a plunger in a microsyringe such as usually used in
gas chromatography. In the case of the invention, immobilized ionic
liquids and absorbed, adsorbed and immobilized diionic liquid salts are
contemplated. The plunger is depressed, exposing the fiber and the fiber
is then dipped into the sample of interest. The plunger can then be
withdrawn to pull the fiber back into the barrel of the syringe, or at
least the barrel of the needle for protection and transport. The syringe
can then be injected through the septum of a gas chromatograph or some
other device and the fiber thereby inserted into the column by
redepressing the plunger of the microsyringe. The heat used in GC then
volatilizes or otherwise drives the bound sample off where it is carried
by the mobile phase through the GC column, allowing for separation and/or
identification. It can also be eluted by a liquid mobile phase in an HPLC
injector or unbuffer capillary electrophoresis.

[0296] More specifically, solid phase microextraction is a technique in
which a small amount of extracting phase (in this case an ionic liquid
and preferably a diionic liquid salt in accordance with the present
invention) is disposed on a solid support, which was then exposed to a
sample for a period of time. In situations where the sample is not
stirred, a partitioning equilibrium between a sample matrix and the
extraction phase is reached. In cases where convection is constant, a
short time pre-equilibrium extraction is realized and the amount of
analyte extracted is related to time. Quantification can then be
performed based on the timed accumulation of analysis in the coating.
These techniques are usually performed using open bed extraction concepts
such as by using coated fibers (e.g., fused silica similar to that used
in capillary GC or capillary electrophoresis, glass fibers, wires, metal
or alloy fibers, beads, etc.), vessels, agitation mechanism discs and the
like. However, in-tube approaches have also been demonstrated. In-tube
approaches require the extracting phase to be coated on the inner wall of
the capillary and the sample containing the analyte of interest is
subject to the capillary and the analytes undergo partitioning to the
extracting phase. Thus, material can be coated on the inner wall of a
needle, for example, and the needle injected without the need for a
separate solid support.

[0297]FIG. 8 shows an example of an SPME device (1). A stainless steel
microtube 40 having an inside diameter slightly larger than the outside
diameter of, for example, a fuse silica rod 60 is used. Typically, the
first 5 mm is removed from a 1.5 cm long fiber, which is then inserted
into the microtubing. High temperature epoxy glue is used to permanently
mount the fiber. Sample injection is then very much like standard syringe
injection. Movement of the plunger 30 allows exposure of the fiber 60
during extraction and desorption and its protection in the needle 20
during storage and penetration of the septum. 10 shows the barrel of the
microsyringe, 50 shows the extreme end of the stainless steel microtube
in which the silicon fiber is mounted. Another version of a syringe
useful for SPME in accordance with the present invention is illustrated
in FIG. 9. Syringe 2 can be built from a short piece of stainless steel
microtubing 130 to hold the fiber. Another piece of larger tubing 120
works as the needle. A septum 110 is used to seal the connection between
the microtubing 130 and the needle 120. The silica fiber 140 is exposed
through one end of the microtubing 130 and the other end is blocked by a
plunger 100. Withdrawing plunger 100 retracts microtubing 130 and the
fiber 140 into the barrel of the device, the needle 120. Depressing
plunger 100 reverses this process. These are but exemplary structures and
any syringe device, including those containing a needle or tube with the
ionic liquid immobilized on the inner surface thereof are also
contemplated.

[0298] Any monoionic liquid or diionic liquid salt may be used in
accordance with the present invention. Diionic liquids such as those
shown immediately below can be absorbed or adsorbed onto a solid support
as previously described.

##STR00022##

[0299] In addition, ionic liquids, both monoionic and diionic liquid salts
in accordance with the present invention can be immobilized by being
bound or cross-linked to themselves and to a solid support as previously
discussed in connection with manufacturing capillary GC columns. To do
so, however, the species used should have at least one unsaturated group
disposed to allow reaction resulting in immobilization. See for example
the monocationic and dicationic species immediately below.

##STR00023##

[0300] Another type of SPME technique is known as task specific SPME or
TSSPME. Task specific SPME allows for the separation or removal, and
therefore the detection of particular species. These can include, for
example, mercury and cadmium, although the technique is equally
applicable to other materials. The concept is exactly the same as
previously described with regard to SPME. However, in this instance, the
ionic liquids or diionic liquids used are further modified such that they
will specifically interact with a particular species. Those shown below,
for example, may be used in the detection of cadmium and mercury
(Cd2+ or Hg2+). The first monocationic material can be coated,
absorbed or adsorbed onto a fiber as previously discussed. A diionic
liquid salt can also be absorbed or adsorbed in known fashion. The second
and third ionic liquid materials illustrated below, the first monoionic
and the second dicationic, by virtue of the presence of unsaturated
groups, can be more easily immobilized on a solid support using
techniques analogous to those described previously with regard to
cross-linking in connection with manufacturing capillary GC columns.

##STR00024##

[0301] Finally, a particular sample can be suspended in a matrix that
includes ionic liquids and preferably diionic liquid salts in accordance
with the present invention. This matrix can be loaded or immobilized on
the fiber of an SPME syringe as described above and then injected into a
mass spectrometer to practice a technique known as SPME/MALDI mass
spectrometry. The matrix is exposed to a UV laser. This causes the
volatilization or release of the sample much as heat does in a GC. This
allows the sample to enter mass spectrometer where it can be analyzed.
Ionic materials which can be used as a matrix include, without
limitation:

[0302] The invention provides a method of detecting a charged molecule
having a single charge (+1 or -1) using electrospray ionization-mass
spectrometry (ESI-MS). In the method, a suitable amount of the diionic
species of the invention having the opposite charges of the molecule of
interest is added to the sample. The diionic species and the charged
molecule form a salt complex. The salt complex is generally a solid.
Because the diionic species has two charges, when complexed with the
charged molecule, the complex has a net charge. The complex is then
detected using ESI-MS. The formation of the complex converts the charged
molecule into an ion having a higher mass to charge ratio m/z, which can
be transferred by ESI more efficiently due to mass discrimination. The
present invention thus provides an ESI-MS method with substantially
improved selectivity and sensitivity. Preferred is the use of dicationic
species.

[0303] In one embodiment, the method of the invention includes selecting a
diionic species that has a desired composition and structure, e.g.,
desired charged group or a desired mass or a combination thereof. The
charged group can be selected based on the composition and structure of
the charged molecule to be detected. Preferably, the diionic species is
specific for the charged molecule to be detected. Thus, it is preferable
that the diionic species is such that it binds strongly with the charged
molecule to be detected. More preferably, the charged group of the
diionic species is such that it does not bind strongly with other charged
molecules different from the molecule of interest in the sample.
Employing a diionic species that is specific for a charged molecule of
interest allows high selectivity in detecting the charged molecule. Use
of diionic species having two different ionic groups may offer particular
advantages in tailoring the affinities for different molecules for
detection.

[0304] The mass of the diionic species is preferably selected to achieve
optimal detection by the mass spectrometer. In general, a diionic species
having a large mass is used. The diionic species is preferably such that
the complex has a m/z higher than 50. Most commercial single quadrupole
mass spectrometers are designed to have their optimum performance at m/z
values significantly higher than 100. In another preferred embodiment,
the diionic species is selected such that the complex has a m/z
significantly higher than 100, e.g., at least about 200, at least about
300, or at least about 400. A person skilled in the art will understand
that the mass of the diionic species depends on the sizes of the charged
groups as well as the bridging group. One or more of these can be varied
to obtain a diionic species of desired mass.

[0305] In another embodiment, the method of the invention includes
selecting a diionic salt that dissociates with high yield. This can be
achieved by selecting a diionic salt containing suitable counter ions. In
cases where a diionic salt having desired ionic groups but less desirable
counter ions, it can be converted to a diionic salt containing the
desired counter ions by anion exchange. In a specific embodiment, a
fluoride salt is used, which, if not yet available, can be converted from
a dihalide, a bromide or an iodide salt by anion exchange.

[0306] In another embodiment, the method further includes a step of
performing ion chromatography prior to the addition of the diionic
species.

[0307] Several dicationic species were used in detecting perchlorate
(ClO4.sup.-). In a preferred embodiment, the invention provides a
method of detecting a charged molecule of -1 charge other than
perchlorate (ClO4.sup.-) by mass spectrometry using a dicationic
species of the invention. In another embodiment, the invention provides a
method of detecting perchlorate (ClO4.sup.-) by mass spectrometry
using a dicationic species of the invention which is not one of the
dicationic species I-X. In still another embodiment, the invention
provides a method of detecting a charged molecule of -1 charge by mass
spectrometry using a "unsymmetric" dicationic species of the invention.
In still another embodiment, the invention provides a method of detecting
a charged molecule of -1 charge by mass spectrometry using a chiral
dicationic species of the invention.

[0308] In another preferred embodiment, the invention provides a method of
detecting a charged molecule of +1 charge by mass spectrometry using a
dianionic species of the invention. Any one of the dianionic species
described above can be used.

[0309] In still another preferred embodiment, the invention provides a
method of detecting a plurality of different charged molecules of +1 or
-1 charge by mass spectrometry using a plurality of different diionic
species of the invention. Each of the diionic species is selected to
specifically bind one of the different charged molecules. Preferably, the
different diionic species have different masses such that the complexes
formed with their respective charged molecules can be detected
separately.

[0310] Mass spectrometry can be carried out using standard procedures
known in the art.

[0311] In another aspect of the present invention, there are provided a
mixture comprising both the diionic liquid salts of the invention and
traditional stationary phase material such as but not limited to
polysiloxanes, PEGs, methylpolysiloxances, phenyl substituted
methylpolysiloxance, nitrile substituted methylpolysiloxance, carbowax.
Such mixture (mixed stationary phase or "MSP") can be used as stationary
phases in chromatography such as gas chromatography, liquid
chromatography and high performance liquid chromatography as well as in
SPE and SPME. Both dicationic salt and dianionic salt can be used for
this purpose. The MSPs can be non-cross-linked (e.g., absorbed or
adsorbed on a solid support or column), can be "partially" cross-linked
or "more highly" cross-linked (i.e., immobilized on a solid support or
column). The diionic liquid salts may also be cross-linked or otherwise
reacted with the traditional stationary phase material or merely mixed
therewith.

[0312] Thus, in one embodiment, the invention provides MSPs comprising at
least one of the diionic liquid salts of the invention and at least one
traditional stationary phase material at a suitable proportion.
Appropriate combinations of the diionic liquid salt(s) and the
traditional stationary phase material(s) for producing the MSP is based
on the particular application as are the proportions of the diionic
liquid salt(s) and the traditional stationary phase material(s) in the
MSP. In a preferred embodiment, the ratio of the diionic liquid salt and
the traditional stationary phase material in the MSP is from about 1:9
(i.e., about 10% of diionic liquid salt and 90% of traditional stationary
phase material) to about 9:1 (i.e., about 90% of diionic liquid salt and
10% of traditional stationary phase material), about 1:3 (i.e., about 25%
of diionic liquid salt and 75% of traditional stationary phase material)
to about 3:1 (i.e., about 75% of diionic liquid salt and 25% of
traditional stationary phase material), about 1:2 (i.e., about 33% of
diionic liquid salt and 67% of traditional stationary phase material) to
about 2:1 (i.e., about 67% of diionic liquid salt and 33% of traditional
stationary phase material), or about 1:1 (i.e., about 50% of diionic
liquid salt and 50% of traditional stationary phase material) (w/w).
Chromatography employing MSP may perform better, e.g., having higher
selectivity, than chromatography employing diionic liquid salts or the
traditional stationary phase alone. As an example, an MSP comprising a
simple mixture of about 67% (dibutyl imidazolium)2((CH2)9
and 33% of methylpolysiloxance with 5% phenyl substitution was prepared
and used to coat a column. This MSP was shown to exhibit better
separation of an essential oil. Cross-linked version of the MSP can also
be used.

[0313] In addition, the invention also provides methods of preparing MSPs,
solid supports and/or columns containing same, the MSPs, solid supports,
syringes, tubes, pipettes tips, needles, vials, and columns themselves,
and the use of columns and solid supports containing such MSPs in
chromatography and other analytical or separation techniques such as
those described elsewhere herein.

Example A

Example 1

[0314] Compound #2

[0315] Synthesis of 2 involved adding 15.0 mL (0.148 mol) of
1,3-dibromopropane dropwise to 23.5 mL (0.295 mol) of 1-methylimidazole
in a round bottom flask under constant stiffing at room temperature. The
reaction was complete within 2 hours. The bromide salt was dissolved in
100 mL water and extracted with three 25 mL aliquots of ethyl acetate.
Water was removed under vacuum heating and the remaining salt was dried
under a P2O5 vacuum. Synthesis of the NTf2.sup.- salt
consisted of dissolving 10 grams (0.03 mol) of the bromide salt in
100-150 mL water. Two molar equivalents (0.06 mol, 3.92 grams) of
N-lithiotrifluoromethylsulfonimide were dissolved in 50 mL of water in a
separate beaker and added directly to the bromide salt. The solution was
allowed to stir for 12 hours. The top water layer was removed to leave
the ionic liquid. Three additional 30 mL aliquots of water were added and
extracted with the ionic liquid until the ionic liquid passed the silver
nitrate test. The ionic liquid was then dried using rotary evaporation
and then further dried under a P2O5 vacuum.

Example A

Example 2

[0316] Compound #7

[0317] Synthesis of 7 involved adding 15.0 mL (0.098 mol) of
1,6-dibromohexane dropwise to 15.6 mL (0.196 mol) of 1-methylimidazole in
a round bottom flask under constant stirring at room temperature. The
reaction was complete within 2 hours. The bromide salt was dissolved in
100 mL water and extracted with three 25 mL aliquots of ethyl acetate.
Water was removed under vacuum heating and the remaining salt was dried
under a P2O5 vacuum. Anions were exchanged by dissolving 10
grams (0.024 mol) of the bromide salt in ˜150 mL acetone. Two molar
equivalents of sodium tetrafluoroborate (0.049 mol, 5.38 grams) were then
directly added to the acetone mixture. After allowing 24 hours for
complete mixing, sodium bromide was filtered off to leave the pure ionic
liquid. The sample was then subjected to silver nitrate to ensure no
silver bromide precipitate was present. Acetone was removed under vacuum
and the remaining ionic liquid dried under a P2O5 vacuum.

Example A

Example 3

[0318] Compound #17

[0319] Synthesis of 17 involved adding 15.0 mL (0.074 mol) of
1,9-dibromononae dropwise to 19.4 mL (0.148 mol) of 1-butylimidazole in a
round bottom flask under constant stirring at room temperature. The
reaction was complete after 5 hours. The resulting viscous liquid was
dissolved in 100 mL water and extracted with three 35 mL aliquots of
ethyl acetate. Water was removed under vacuum heating and the remaining
salt was dried under a P2O5 vacuum.

Example A

Example 4

[0320] Compound #25

[0321] Synthesis of 25 involved dissolving 13.1 mL (0.148 mol) of
1,2-dimethylimidazole in 125 mL 2-propanol and adding 15.0 mL (0.074 mol)
of 1,9-dibromononane dropwise in a round bottom flask equipped with a
condenser and refluxing at 95° C. for 24 hours. After removal of
2-propanol under vacuum, the bromide salt was dissolved in 100 mL water
and extracted with three 35 mL aliquots of ethyl acetate. Water was
removed under vacuum heating and the remaining salt was dried under a
P2O5 vacuum. Synthesis of the NTf2.sup.- salt consisted of
dissolving 10 grams (0.02 mol) of the bromide salt in 100-150 mL water.
Two molar equivalents (0.04 mol, 11.48 grams) of
N-lithiotrifluoromethylsulfonimide were dissolved in 50 mL of water in a
separate beaker and added directly to the bromide salt. The solution was
allowed to stir for 12 hours. The top water layer was removed to leave
the ionic liquid. Three additional 30 mL aliquots of water were added and
extracted with the ionic liquid until the ionic liquid passed the silver
nitrate test. The ionic liquid was then dried using rotary evaporation
and then further dried under a P2O5 vacuum.

Example A

Example 5

[0322] Compound #29

[0323] Synthesis of 29 involved dissolving 25.0 g (0.158 mol) of
1-benzylimidazole in 100 mL 2-propanol and adding 25.9 grams (0.079 mol)
of 1,12-dibromododecane in a round bottom flask equipped with a condenser
and refluxing at 95° C. for 24 hours. Due to the hydrophobicity of
the salt, it was found to be quite insoluble in water. Therefore, it was
washed with ethyl acetate (˜75 mL) and then dried under
P2O5. Because the bromide salt as not soluble in water, 10.0
grams (0.016 mol) was dissolved in methanol with stiffing. To another
beaker was added 8.9 grams (0.031 mol) of
N-lithiotrifluoromethylsulfonimide with approximately 50 mL of water. The
two contents were mixed the mixture allowed to stir for nearly 5 hours.
The methanol-water solution was then removed and the liquid washed with
water and then further dried under vacuum and under P2O5.

Example A

Example 6

[0324] Compound #31

[0325] Synthesis of 31 involved dissolving 13.0 mL (0.128 mol) of
1,3-dibromopropane in 100 mL 2-propanol and adding 26.6 mL (0.256 mol) of
1-methylpyrrolidine in a round bottom flask equipped with a condenser and
refluxing at 95° C. for 24 hours. After removal of 2-propanol
under vacuum, the bromide salt was dissolved in 100 mL water and
extracted with three 35 mL aliquots of ethyl acetate. Water was removed
under vacuum heating and the remaining salt was dried under a
P2O5 vacuum.

Example A

Example 7

[0326] Compound #35

[0327] Synthesis of 35 involved dissolving 12.0 mL (0.059 mol) of
1,9-dibromononane in 100 mL 2-propanol and adding 12.3 mL (0.118 mol) of
1-methylpyrrolidine in a round bottom flask equipped with a condenser and
refluxing at 95° C. for 24 hours. After removal of 2-propanol
under vacuum, the bromide salt was dissolved in 100 mL water and
extracted with three 35 mL aliquots of ethyl acetate. Water was
P2O5 vacuum. Synthesis of the NTf2 salt consisted of
dissolving 10 grams (0.02 mol) of the bromide salt in 100-150 mL water.
Two molar equivalents (0.04 mol, 11.48 grams) of
N-lithiotrifluoromethylsulfonimide were dissolved in 50 mL of water in a
separate beaker and added directly to the bromide salt. The solution was
allowed to stir for 12 hours. The top water layer was removed to leave
the ionic liquid. Three additional 30 mL aliquots of water were added and
extracted with the ionic liquid until the ionic liquid passed the silver
nitrate test. The ionic liquid was then dried using rotary evaporation
and then further dried under a P2O5 vacuum.

Example A

Example 8

[0328] Compound #38

[0329] Synthesis of 38 involved dissolving 13.0 mL (0.064 mol) of
1,9-dibromononane in 100 mL 2-propanol and adding 20.0 mL (0.128 mol) of
1-butylpyrrolidine in a round bottom flask equipped with a condenser and
refluxing at 95° C. for 24 hours. After removal of 2-propanol
under vacuum, the bromide salt was dissolved in 100 mL water and
extracted with three 35 mL aliquots of ethyl acetate. Water was removed
under vacuum heating and the remaining salt was dried under a
P2O50.5 vacuum. Synthesis of the NTf2.sup.- salt consisted
of dissolving 10 grams (0.019 mol) of the bromide salt in 100-150 mL
water. Two molar equivalents (0.037 mol, 10.62 grams) of
N-lithiotrifluoromethylsulfonimide were dissolved in 50 mL of water in a
separate beaker and added directly to the bromide salt. The solution was
allowed to stir for 12 hours. The top water layer was removed to leave
the ionic liquid. Three additional 30 mL aliquots of water were added and
extracted with the ionic liquid until the ionic liquid passed the silver
nitrate test. The ionic liquid was then dried using rotary evaporation
and then further dried under a P2O5vacuum.

Example A

Example 9

[0330] Procedure For the Synthesis of Di-Cationic Phosphonium ILs

1,10-decane-tripropyl phosphonium bromide

##STR00037##

[0331] was synthesized according to the following procedure. The preceding
ionic liquid was synthesized according to the following procedure: In a
round bottom flask (100 mL), 1,10-dibromodecane (3.7 g) was dissolved in
isopropyl alcohol (50-75 mL). At room temperature, tripropylphosphine
(6.5 mL) was added to the solution. The resulting solution was stirred
and heated under reflux for 48 hrs. After this time, the solution was
cooled to room temperature. Rotoevaporation of the solvent followed by
drying in vacuum over phosphorous pentoxide, yielded a white crystalline
product with a melting point of approximately 50° C.

Example A

Example 10

Synthesis of "Unsymmetric" Diionic Salts

[0332] The following compounds are used for the synthesis: the alkyl
linkage compounds:

##STR00038##

the aryl linkage compounds:

##STR00039##

the PEG linkage compounds:

##STR00040##

[0333] The "unsymmetric" dicationic ILs are synthesized from
dibromo-linkers according to the following steps:

[0334] First, the monocation intermediate is synthesized by reacting with
the linkage compound that is in excess during the reaction to decrease
the symmetric dicationic byproduct. For an example, the synthesis of
ammonium-based monocation is shown in Scheme 1.

##STR00041##

[0335] Then, the unsymmetrical diicationic ionic compound with the desired
anion is synthesized by the metathesis reaction from the dibromide
compound that is obtained as an example of ammonium-imidazonium based IL
in Scheme 2.

##STR00042##

[0336] Next, the unsymmetrical diicationic ILs are synthesized from the
linkage compound having both bromo- and hydroxyl-groups, shown as an
example of ammonium-imidazonium based IL in Scheme 3.

##STR00043##

Example B

Polymeric Ionic Liquids

Example B

Example 1

[0337] A series of three homologous PILs are used to extract esters and
fatty acid methyl esters (FAMEs) from aqueous solution. To examine the
effect of the matrix on the coatings, extractions were carried out in a
synthetic wine solution followed by recovery experiments in two real wine
samples. The extraction performance of the PIL-based coatings is compared
to that of the commercial polydimethylsiloxane (PDMS) and polyacrylate
(PA) coatings.

[0341] The synthesis of all ionic liquid monomers and polymers involved
the use of the following reagents, which were all obtained from
Sigma-Aldrich (Milwaukee, Wis., USA): vinyl imidazole,
2,2'-azo-bis(isobutyronitrile), hexyl chloride, dodecyl bromide, and
hexadecyl bromide. Lithium bis(trifluoromethanesulfonyl)imide was
obtained from SynQuest Labs (Alachua, Fla., USA).

[0342] Synthetic wine samples were prepared using (+)-tartaric acid
purchased from Sigma-Aldrich (Milwaukee, Wis., USA). Deuterated
chloroform and dimethylsulfoxide were obtained from Cambridge Isotope
Laboratories (Andover, Mass., USA). Deionized water (18.2 Megaohms/cm)
was obtained from a Milli-Q water purification system (Millipore,
Bedford, Mass., USA) and was used in the preparation of all aqueous
solutions. Propane and microflame brazing torches were purchased from
Sigma-Aldrich (Milwaukee, Wis., USA).

[0343] The solid phase microextraction (SPME) devices were constructed
using a 5 μL syringe purchased from Hamilton (Reno, Nev., USA) and
0.10 mm I.D. fused silica capillary obtained from Supelco (Bellefonte,
Pa., USA). Commercial SPME fibers of polydimethylsiloxane (PDMS, film
thicknesses of 7 μm and 100 μm) and polyacrylate (PA, film
thickness of 75 μm) were obtained from Supelco (Bellefonte, Pa., USA).
A fiber holder purchased from the same manufacturer was used for manual
injection of the commercial fibers. Amber glass vials (20 mL) with
PTFE/Butyl septa screw caps supplied by Supelco (Bellefonte, Pa., USA)
were used in the study. PTFE stir bars were obtained from Fisher
Scientific (Fair Lawn, N.J., USA) and were used to perform all
extractions at a constant stirring rate of 900 rpm on a coming stir plate
(Nagog Park Acton, Mass., USA).

[0344] FIG. 16 is a non-limiting example of a system for headspace
extraction.

Methods

[0345] An eight minute desorption time was used for all fibers. Analyte
carryover (<1%) was periodically checked by reinserting the fiber into
the injector for an additional 5 minutes following the previous
desorption step. In all extractions, the volume of the aqueous solution
was 15 mL. All analyses were carried out using an Agilent 6850N gas
chromatograph (Agilent Technologies, Palo Alto, Calif., USA) equipped
with a flame ionization detector (FID). All separations were performed
using a DB-1 polydimethylsiloxane capillary column (30 m×0.32 mm
I.D., 0.25 μm film thickness) purchased from Alltech (Deerfield, Ill.,
USA).

[0346] The following temperature program was used for the separation of
the ester mixture: initial temperature of 60° C. held for 3 min
and then increased to 165° C. employing a ramp of 5°
C./min. The carrier gas was helium with a flow rate of 1 mL/min. Both GC
injector and detector temperatures were maintained at 250° C.
using splitless injection, the detector make-up flow of helium at 45
mL/min, the hydrogen flow at 40 mL/min, and the air flow at 450 mL/min.
Agilent Chemstation software was used for data acquisition.

[0348] The three IL monomers (1-vinyl-3-hexyliimidazolium chloride,
1-vinyl-3-dodecylimidazolium bromide, and 1-vinyl-3-hexadecylimidazolium
bromide) were produced by mixing 0.06 moles of 1-vinylimidazole with 0.06
moles of the corresponding alkyl halide in -20 mL of 2-propanol.

[0349] The mixture was then allowed to react at 60° C. for 16 hours
with constant and vigorous stirring. After cooling to room temperature,
2-propanol was evaporated under vacuum. The IL product was then dissolved
in 20 mL of water and extracted five times with 10 mL portions of ethyl
acetate. Ethyl acetate was then removed under vacuum at 80° C. and
the product was dried in a vacuum oven at 70° C. for two days. The
purity was confirmed by 1H-NMR before subjecting the monomer to
polymerization.

[0350] Polymerization of the IL monomers (see FIG. 11) was carried out by
free radical polymerization [24]. Briefly, 3.0 grams of the purified IL
monomer was dissolved completely in 30 mL of chloroform. To this mixture,
0.06 grams (-2%) of the free radical initiator AIBN
(2,2'-azo-bis(isobutyronitrile)) was added and refluxed for 3 hours at
70° C. under an inert N2 atmosphere. Chloroform was
subsequently removed and the product dried under vacuum at 80° C.
When needed, the polymerization step was repeated until the peaks
represented by the vinyl group in the 1H-NMR disappeared.

[0351] FIG. 12 shows 1H-NMR spectra of the
1-dodecyl-3-vinylimidazoliumm bromide monomer and the corresponding
poly(1-dodecyl-3vinylimidazolium) bromide polymer. A comparison of the
1H-NMR spectra of the PIL to that of the IL monomer shows the
disappearance of the double bond originating from the vinyl-substituted
monomer (8=5.4 ppm, 5.9 ppm, and 7.3 ppm) and the broadening of the
signals due to hindered molecular tumbling. The halide anion was
exchanged with the bis[(trifluoromethyl)sulfonyl]imide (NTf2) anion by
metathesis anion exchange. Briefly, 0.10 moles of an aqueous solution of
lithium bis[(trifluoromethyl) sulfonyl]imide was mixed with 0.10 moles of
an aqueous solution of the polymerized IL and stirred overnight. The
resulting product was filtered and extracted with three 15 mL portions of
water. The resulting IL polymer was dried under vacuum for two days at
70° C.

[0355] The SPME devices were constructed using a novel modification of the
procedure first described by Pawliszyn [1]. The polyimide polymer was
subsequently removed from the last 1.0 cm segment of the fiber using a
high temperature flame followed by sealing of the end of the capillary
using a microflame torch. The fiber was then washed with methanol,
hexane, acetone and dichloromethane followed by a 10 minute conditioning
step in the GC injection port at 250° C.

[0356] To make the PIL amendable to coating as a thin film on the fused
silica fiber support, a solution was prepared by mixing the PIL in
acetone at a ratio of 9:1 (v/v). The conditioned bare fused silica fiber
was dipped into the PIL solution, held for 20 seconds, and removed from
the coating solution and allowed to dry in the air for 10 minutes. Prior
to performing extractions, the coated fibers were conditioned at
250° C. in the GC injection port for 10 minutes to eliminate
residual solvents from the fiber support.

[0357] Headspace Extraction of Esters

[0358] Individual stock standard solutions of esters were prepared in
HPLC-grade acetonitrile at a concentration of 1000 mg L-1. These
standard solutions were stored at 4° C. and were used to prepare
daily aqueous working solutions containing a total acetonitrile content
lower than 3% (v/v). All headspace extractions were carried out using 20
mL extraction vials containing 15.0 mL of the aqueous working solution.
The sorption-time profiles were obtained by extracting the studied
analytes at a concentration of 200 μL-1 at varying extraction
time intervals using a constant stir rate of 900 rpm at 23° C. The
calibration curves were obtained in Milli-Q water at an optimized
extraction time of 50 minutes with a total of at least 10 calibration
concentrations.

[0359] To determine the effect of the matrix on the extraction of esters
and FAMEs, extractions were performed in a synthetic wine sample as well
as a red wine and white wine sample (Cranelake, Calif., USA). The
synthetic wine solution was prepared according to a previously reported
formulation [25] by dissolving 3.5 g L-1 of (+)-tartaric acid in a
hydro-alcoholic solution (12% v/v ethanol) and using sodium hydroxide to
adjust the pH to 3.5. The calibration curves of all synthetic wine
samples were constructed using a 50 minute extraction time with a total
of 10 calibration levels. Analyte recovery experiments in the real wine
samples were performed at two concentration levels, namely 100
μL-1 and 400 μg L-1.

[0362] The halogen anions were subsequently exchanged with the
bis[(trifluoromethyl)sulfonyl]imide anion (NTf2.sup.-) in an effort
to increase the thermal stability of the PIL while also imparting more
hydrophobic character to the stationary phase coating. The PILs were then
coated onto fused silica supports by dipping the fiber support into a
dilute solution of the PIL in acetone.

[0363] FIGS. 13A-13D show SEM photos of the bare fused silica fiber (FIG.
13A) and various angles of the fused silica fiber after coated with the
poly(ViHDIm+ NTf2.sup.-) PIL (see FIGS. 13B-13D).

[0364] Using the PM-based coatings, the inventors herein obtained a
smooth, homogeneous coating on the fiber (as opposed to neat ILs, which
have a tendency to form droplets on the surface of the fused silica
support). Based on the SEM photos, the approximate film thickness of the
PM coating on the fiber is estimated to be approximately 12-18 μm.

[0365] To demonstrate that the PIL stationary phase is responsible for the
extraction of the analytes examined, blank extractions using a 1.0 cm
fused silica fiber containing no stationary phase were carried out on an
aqueous solution of esters at a concentration of 500 μg L-1. This
data, not shown, revealed no appreciable extraction of analytes by the
bare fused silica support.

[0368] After initial conditioning of the PIL fibers, sorption-time
profiles were obtained in an aqueous solution using headspace extraction.
Throughout the construction of the sorption profile, the reproducibility
of the fiber was examined by performing triplicate extractions at various
time intervals which yielded RSD values lower than 15%. The sorption-time
profile for the poly(ViHIm+ NTf2.sup.-) coated fiber, shown in
FIG. 14, were obtained by monitoring the area counts of each of the
eleven analytes versus the fiber exposure time.

[0369] Equilibration was quickly reached in approximately 20 to 30 minutes
for most analytes, except for a few longer chained FAMEs (e.g., methyl
undecanoate and methyl laurate), which attained equilibrium at longer
times. Similar sorption-time profiles were obtained for the other
PIL-based coatings. Fifty minutes was selected as the optimized
extraction time of these analytes using all fibers for the entire
calibration study.

[0370] Analytical Performance.

[0371] Calibration curves were obtained for all three PIL-based coatings
as well as the PA and PDMS coatings in Milli-Q water.

[0373] The correlation coefficients varied between 0.986 and 0.999. It can
be observed from Table 1 (FIG. 21) that the sensitivity for a given
individual analyte is nearly the same among the three PIL-based coated
fibers. The detection limits for most analytes using the PIL-based fibers
ranged between 2.5-50 4 g L-1 where lower detection limits were
obtained for the larger FAMEs. Large increases in sensitivity were
observed with increasing hydrophobicity of the analyte, particularly for
the homologous series of FAMEs.

[0374] For comparison purposes, Table 2 (FIG. 22) lists the calibration
data for three commercial SPME fibers. The two PDMS fibers contain film
thicknesses of 7 μm and 100 pm whereas the PA fiber contains of a 75
μm film thickness. Superior sensitivities and detection limits are
observed with the PDMS and PA fibers employing thicker absorbent
coatings. The sensitivities for most analytes are higher using the
PIL-based stationary phases (approximate film thickness of 12-18 μm)
compared to the PDMS coating employing a 7 μm film thickness, allowing
for lower detection limits. Despite the fact that the 75 μm PA fiber
has a much thicker film compared to the PIL fibers, similar sensitivities
were obtained for several analytes, particularly methyl undecanoate,
methyl laurate, furfural octanoate, and hexyl tiglate.

[0375] A comparison of the sensitivity increase between methyl nonanoate
and methyl decanoate on the poly(ViHDIm+ NTf2.sup.-) coated
fiber revealed a 325% increase in sensitivity compared to a 185% increase
on the 100 μm PDMS fiber, 175% increase on the 7 μm PDMS fiber, and
a 240% increase on the 75 μm PA fiber.

[0376] These examples show that the hydrophobic nature of the PIL imparted
by the alkyl substituents on the imidazolium cation, along with the
bis[(trifluoromethyl)sulfonyl]imide anion, provide solvation
characteristics more similar to the PDMS coating rather than the PA
coating while often producing higher sensitivity and selectivity than
both.

[0377] Evaluation of Matrix Effect.

[0378] The analyte distribution coefficient between the solution and fiber
coating are dependent on the nature of the matrix [26]. To evaluate the
effect of matrix interference on the accuracy of the polymeric ionic
liquid-based absorbent coatings, a calibration study of the esters and
FAMEs was first carried out in synthetic wine. The primary advantage of
employing a synthetic wine matrix is that the effect of ethanol content
on the observed extraction efficiency, selectivity, and sensitivity can
all be studied independent of other volatile compounds that are widely
present in all wines.

[0379] As shown in FIG. 23--EXAMPLE B--Table 3 and FIG. 24--EXAMPLE
B--Table 4, respectively, the sensitivity decreased for all fibers when
the extractions were carried out in a synthetic wine solution consisting
of approximately 12% (v/v) of ethanol compared to when they were
performed in Milli-Q water.

[0380] For the PIL-based coatings, the largest drop in sensitivity between
the two matrices was observed for the smaller esters including isopropyl
butyrate, ethyl valerate, and methyl caproate. Conversely, the 7 μm
PDMS fiber exhibited the smallest sensitivity drop for these analytes.
All PIL-based fibers exhibited greater sensitivity with in the increase
in the alkyl chain of the FAME whereas, in general, a smaller enhancement
in sensitivity was observed for the 7 micron PDMS fiber. Despite the
matrix interference caused by ethanol, the detection limits of all
PIL-based fibers were better than that of the 7 μm PDMS fiber.

[0381] To examine the effect of a real matrix, recovery studies were
performed in both red and white wine samples. An extraction of both neat
wine samples using two PDMS fibers (7 μm and 100 μm) and the three
PIL fibers revealed the concentration of all esters and FAMEs examined in
this study to be below the detection limit or absent from the sample.
Using the calibration curves generated in the synthetic wine, recoveries
were determined in triplicate at two spiking calibration levels, namely
100 μL-1 and 400 L-1.

[0382] As shown in FIG. 25--EXAMPLE B--Table 5, the precision of the red
wine sample using the PIL-based fibers was best at the higher spiking
level yielding RSD values below 12%. Due to the fact that the detection
limits for most analytes in the synthetic wine samples ranged from 2.5-50
μg L-1, it is understandable that the more complicated wine
matrix would exhibit poorer repeatability.

[0383] Recoveries for the PIL-based fibers at the higher spiking level
ranged from 70.2% for methyl laurate to 115.1% for ethyl valerate. Using
the 7 μm PDMS fiber, recoveries ranged from 61.9% for methyl laurate
to 102.9% for isopropyl butyrate. The thicker PDMS coating (100 μm)
yielded recoveries ranging from 74.4% for methyl laurate to 96.9% for
methyl enanthate.

[0385] Recovery and precision data for the white wine sample is shown in
FIG. 26--EXAMPLE B Table 6. Recoveries for the PIL-based fibers at the
higher spiking level ranged from 74.0% for ethyl valerate to 132.4% for
furfuryl octanoate with RSD values lower than 19.0%. For the 7 PDMS
fiber, recoveries ranged from 48% for methyl laurate to 96.7% for methyl
caproate with RSD values lower than 19.0%. The results clearly indicate
that the performance of the PIL-based fibers in terms of recovery and
repeatability is often superior to that of the PDMS fiber of similar film
thickness.

[0387] FIG. 18 is a chart showing figures of merit for PIL-based
extractions in wine.

[0388] Fiber Lifetime

[0389] The inventors also made polymeric ionic liquids that form stable,
even fibers while exhibiting superior thermal stability. Two of the
PIL-coated fibers [poly(ViHIm+ NTf2.sup.-) and
poly(ViDDIm+ NTf2.sup.-)] were utilized in approximately 150
extractions while retaining RSD values lower than 14-18%.

[0390] To attain high fiber lifetimes, care was taken during the
fabrication of the fiber assembly, coating of the fiber, and the
subsequent extraction/desorption steps, which make the fragile fused
silica susceptible to breakage. In certain embodiments, the structural
design of the employed PIL may be important in achieving high thermal
stability. Thus, in one particular embodiment, the
bis[(trifluoromethyl)sulfonyl]imide salts paired with large, bulky
cations can be used to produce IL monomers with exceptional thermal
stability.

[0391] Further, in certain embodiments, it may be advantageous that the
PIL be free of residual halides following anion metathesis as halides are
known to significantly lower the thermal stability of the product [13,
27]. In addition, in certain embodiments, it may be advantageous that the
desorption temperature and desorption time be optimized to prolong the
lifetime of the coating material.

Example B

Example 3

[0392] Extraction of PTEXs

[0393] By polymerizing IL monomers to form polymeric ionic liquids (PILs),
stable absorbent coatings were developed for the extraction of benzene,
toluene, ethyl benzene, and xylenes in gasoline. The reproducibility and
loading of the extraction phase has been improved by modifications to the
design of the SPME assembly.

[0394] FIGS. 19A-19C are graphs showing the quantitative analysis of PTEX
compounds in gasoline. FIG. 19A shows the sorption time profile. FIG. 19B
shows the calibration curves. FIG. 19C shows the gas chromatogram of BTEX
in gasoline. FIG. 20 is a chart showing the figures of merit for C16
PIL-based extraction in gasoline.

Example B

Example 4

[0395] Ionic Liquid-Based Absorbent Coatings for Microextractions

[0396] The use of ILs as absorbent coatings in solid phase microextraction
(SPME) included the development of an extraction device employing a fused
silica support housed in a shielded syringe assembly. A method was
developed to coat the IL on solid fused silica supports (˜1 cm in
length) by dipping the fiber in a solution of the IL in dichloromethane.
The IL-coated fused silica support was then placed in the injection port
of a GC at 200° C. for 4 minutes to completely remove the organic
solvent.

[0397] FIG. 27A and FIG. 27B show the fused silica support tip coated with
a highly viscous siloxy-based IL, whose structure is shown in the subset.

[0398] Sampling was performed by exposing the fiber to the headspace of an
aqueous analyte solution for a pre-determined amount of time. The
analytes were then desorbed, separated, and detected using GC. Initial
attempts in coating the fused silica support indicated the desirably of
the IL to exhibit two properties: (i) possession of a high viscosity
capable of providing a stable, even coating on the solid support; and,
(ii) possession of a high volatilization temperatures capable of
withstanding the temperatures of the GC injection port (250-300°
C.).

[0399] Despite the fact that high extraction efficiencies were obtained
for a variety of polar and nonpolar analytes, the extraction to
extraction reproducibility was poor with percent relative standard
deviation (% RSD) values from 20-25%. The culprit for this loss in
reproducibility is likely the substantial decrease in IL viscosity when
exposed to the high injection temperatures, thereby prompting the IL to
flow off the fiber and into the injection port.

[0400] The inventors herein have now found that, in certain embodiments,
improvements in the reproducibility can be attained by carrying out the
desorption step using lower injection temperatures (170-200° C.).
For analytes in which higher injection temperatures (>200° C.)
are required (i.e., analytes will low vapor pressures and high boiling
points), the fiber can be re-coated after each extraction which produces
typical % RSD values between 14-18%.

[0401] In addition to neat ILs, linear polymers of ILs have also been
examined as absorbent coatings. In one non-limiting example, the IL
polymer is synthesized by free radical polymerization of the
1-vinyl-3-alkylimidazolium bromide monomer using a free radical such as
azobisisobutylonitrile (AIBN).

[0402] The extent of polymerization is monitored by 1H-NMR to ensure
the absence of any free monomers. The anion of the IL can be readily
exchanged through biphasic anion metathesis.

[0403] Polymerized ILs do not exhibit the same viscosity drop with
elevated temperatures as their monomeric analogs. In addition, the
polymers can be easily dissolved in acetone and dip coated on the fused
silica fiber to result in a thin film of the absorbent coating. The
stability of the film (i.e., resistance to flowing) at elevated
temperatures has resulted in % RSD values in the range of 3-12% and is
highly analyte dependent. Typical % RSD values obtained in routine SPME
are generally not higher than 15%.

[0404] The gas chromatogram shown in FIG. 28 illustrates the headspace
extraction of a mixture containing 27 polar and nonpolar analytes from an
aqueous solution using a polymerized IL fiber support, analogous to that
shown in FIG. 27. The structure of the IL polymer employed as the
absorbent coating is shown as the subset in FIG. 28.

Example B

Example 5

[0405] Ionic Liquid-Coated Supports

[0406] Using the IL-polymer coated support, it is now shown herein that a
desorption temperature and time of 230° C. and four minutes,
respectively, results in the amenability of the fiber to be used up to
approximately 65 extractions before the fiber becomes susceptible to
breakage or the % RSD values increase to over 15%. In addition, headspace
extraction sorption time profiles have been measured for aliphatic
hydrocarbons, fatty acid methyl esters, small-chained esters, and
phthalate esters using both large sample volumes (e.g., 15 mL aqueous
solution with ˜3.9 mL headspace) and small sample volumes (e.g.,
600 μL aqueous solution with ˜400 μL headspace). Upon
reaching the equilibrium time, calibration curves have been obtained for
homologous mixtures of fatty acid methyl esters and small-chained esters.

[0407] FIG. 29--EXAMPLE B Table 7 shows the exceptional linearity of the
analytes studied. Also, additional classes of analytes including
polyaromatic hydrocarbons and polychlorinated biphenyls can be extracted.
The structure of the IL monomer was systematically modified through the
incorporation of longer alkyl chains, aromatic moieties, and
hydroxyl-functionality. Each IL-monomer is then paired with four
different anions (e.g., Br--, NTf2-, PF6--, and BF4--) to show the cation
and anion effects on extraction efficiency.

[0408] A structure/property relationship correlating the IL structure to
solvation characteristics can be conducted by examining IL and IL-polymer
coated supports for two purposes: (i) to study the partitioning of
analytes between ILs and various solvents, and (ii) to utilize the unique
and tunable solvation properties of the IL coating for the development of
new microextraction absorbent coatings.

[0409] Using IL-based absorbent coatings, the solvation characteristics
can be carefully chosen to selectively extract certain analytes from a
complex mixture. For example, acidic analytes can be selectively
extracted from other analytes by utilizing an IL that possesses high
hydrogen-bond basicity. Likewise, aromatic analytes could be selectively
extracted using an IL capable of interacting strongly via π-π
interactions.

Example B

Example 6

[0410] Ionic Liquid Coated Absorbents.

[0411] A dip coating technique used to prepare the IL-coated supports is
successful for ILs that possess high viscosities as they are less prone
to flowing at high desorption temperatures. For less viscous ILs, the IL
film can be re-coated after each extraction to restore the absorbent
coating. To investigate the effects of the IL cation and anion structure
on overall analyte molecule partitioning, initial experiments ILs with
the different cation/anion combinations can be examined.

[0412] Representative structures of such traditional ILs are shown in
FIGS. 30A-30C in which the substituent groups on the 1, 2, and 3
positions of the imidazolium ring can be systematically varied to give
rise to unique cation structures. In addition, other cations such as
pyridinium and pyrrolidinium can also be produced.

[0413] A variety of anions can be paired with given cations to show the
effect of the anion on partitioning. The observed hydrogen bond basicity
of ILs is largely a contribution from the anion whereas the hydrogen bond
acidity appears to originate from the cation. Through modification of
aqueous solution pH, the extent of interaction between acidic and basic
compounds and various IL cations and anions can be shown.

Example B

Example 7

[0414] Immobilized Ionic Liquid Absorbents.

[0415] The partitioning behavior of compounds to IL-polymers that are
formed on the surface of the solid support can be accomplished through
the reaction of the free silanol groups on the surface of the fused
silica support with a vinyl-terminated organoalkoxysilane. FIG. 31 shows
the coating and subsequent free radical reaction to form a thin,
immobilized/crosslinked IP layer on a 1 cm segment of fused silica.

[0416] The vinyl-substituted IL monomers and/or crosslinkers can then be
coated on the support with AIBN and heated to induce free radical
polymerization. In certain embodiments, the degree of crosslinking can
dictate the consistency of the formed polymer with lower degrees of
crosslinker resulting in gel-like materials.

[0417] Extensive crosslinking may likely result in a more rigid,
plastic-like coating. The extent of cros slinking may influence the
mechanism of partitioning (i.e., adsorption versus absorption) and the
overall selectivity for targeted analyte molecules. In addition to
thermally desorbing analytes from the coating material in the injection
port of GC, these robust supports have the advantage of being adaptable
to solvent desorption in HPLC.

[0418] A solvent desorption device coupled to HPLC that accommodates the
extraction devices can thus be used.

Example B

Example 8

[0419] Ionic Liquid Coated Stir Bar Supports.

[0420] For analytes with low solubilities in aqueous solution or under
very dilute conditions, a larger amount of IL may be required to achieve
a measurable partition coefficient.

[0421] FIG. 32 illustrates a procedure for producing thicker films of
immobilized and coated ILs on glass stir bar supports. Following the
coating or immobilization procedure, the stir bar can be added directly
to the biphasic system, stirred, and then be retrieved to
chromatographically determine the concentration of the analytes in the IL
phase.

[0422] Due to the fact that the coating may be much thicker on the stir
bar support compared to that on the fused silica support, a thermal
desorption unit may be required to desorb analytes from the stir bar. The
desorption unit utilizes cryogenic liquid nitrogen to focus the analytes
during the desorption step so that all analytes are subjected to the head
of the GC capillary column in one slug. For more refractory compounds,
HPLC can be used to separate and quantify the analyte molecules. This can
be carried out by choosing the appropriate solvent strength of the mobile
phase and either performing a back extraction or the utilization of an
existing solvent desorption chamber built into the injection system.

Example B

Example 9

[0423] Determination of Partition Coefficients.

[0424] FIGS. 33A-33B show examples of methods and appropriate equilibria
that can be considered in determining the desired partition coefficients.
The equilibria are analogous to those derived previously for solid phase
microextraction. The advantages of measuring partition coefficients using
the proposed microextraction techniques are: (i) small volumes of IL
required to form the absorbent coating; (ii) an extensive range of
analytes can be examined; (iii) identical analytes can be desorbed and
separated by both GC and HPLC allowing for a comparison of partition
coefficients using two different desorption and separation methods; (iv)
the proposed microextraction methods are faster than current shake-flask
methods; and, (v) depending on the solvent properties of the IL and/or
the extent of cros slinking, the aqueous solution can be easily replaced
by an organic solvent to form a biphasic system with the IL.

[0426] The unique solvation properties of ILs can be used to develop
IL-based extraction devices. TSILs represent a class of ILs in which the
cation and/or anion incorporates unique functionality useful for
enhancing distinct interactions to perform desired tasks.

[0427] Use of TSILs.

[0428] A variety of TSILs, examples of which are can be synthesized. For
example, the thioether, thiourea, and urea functionalized ILs (FIGS.
34A-34C) are capable of selectively chelating Cd2+ and Hg2+.
Absorbent coatings of these neat ILs can be examined initially followed
by synthesis of their immobilized analogs. Immobilization can take place
on both the fused silica and stir bar support. This can be accomplished
by incorporating vinyl or allyl moieties into the 3 position of the
imidazolium cation while retaining the task-specific functionality.

[0429] This method of measuring the partition coefficients can allow for
the addition of competing molecules in the biphasic system to determine
any concentration limits that may affect the overall selectivity the TSIL
has for target molecules. In addition, different IL anions can be
examined to probe the effect of the anion on the observed extraction
efficiency of the metal ion. Other conditions such as aqueous solution
temperature, pH, and electrolyte concentration can also be adjusted.

[0430] To detect and quantify pre-concentrated metal ions in the IL, a
back extraction can be performed followed by detection using atomic
absorption spectrophotometry or inductively coupled plasma atomic
emission spectrometry.

[0431] FIG. 35 shows a schematic illustration of on-fiber metathesis anion
exchange using a partially crosslinked IL coating. The Cl.sup.- anions
(left) are being exchanged and replaced by PB6.sup.- (right).

Example B

Example 11

[0432] IL-based CO2 selective absorbent coating

[0433] An intense area of research today lies with the development of new
materials and methods for the sequestration of CO2. Sequestration of
CO2 is particularly important in the purification of sour natural
gas, onboard naval submarines where clean air atmosphere is desired, and
in various industrial processes where scrubbers are typically employed.

[0434] TSILs can be designed to sequester CO2 through the use of
appended amines to the cation core. The molar uptake of CO2 per mole
of TSIL approaches 0.5, demonstrating that the TSILs are sequestering
CO2 in an analogous manner to the standard employed alkanolamines.
The process of CO2 capture is reversible by heating the TSIL to
temperatures around 80-100° C.

[0435] Similar amine-functionalized TSILs can be used to form coated and
immobilized absorbent coatings for the development of task-specific
microextraction devices. Following the extraction and capture of
CO2, the supports can be desorbed and separated using packed column
GC with a thermal conductivity or mass spectrometric detector. Using this
approach, the following objectives can be met: (i) examination of TSIL
CO2 selectivity in the presence of water vapor; (ii) effect of
temperature on CO2 uptake into the TSIL; and (iii) influence of
potential contaminating gases (e.g., H2S, CO, COS) which may
lengthen the equilibrium uptake time of CO2 into the TSIL. The
task-specific extraction device can be incorporated into an industrial
process for the detection and quantification of CO2 in gas streams.

[0436] BBIM-taurate IL-based CO2 Selective Absorbent Coating

[0437] FIG. 36 shows the structure of -1butyl-3-butylimidazolium taurate
(BBIM-taurate). FIG. 37 show a synthetic route for BBIM-taurate. FIG. 38
is the gas chromatogram of BBIM-taurate.

[0441] All laboratory-made SPME devices were constructed using a 5-1 μL
syringe purchased from Hamilton (Reno, Nev., USA) and 0.05 mm I.D. fused
silica capillary obtained from Supelco (Bellefonte, Pa., USA). Commercial
SPME fibers of PDMS (film thickness of 7 μm) and Carboxen®-PDMS
(film thickness of 75 μm) were obtained from Supelco. A fiber holder
purchased from the same manufacturer was used for manual injection of the
commercial fibers. Gas sampling bulbs (250 mL) with thermogreen® LB-1
cylindrical septa were obtained from Supelco and used to perform CO2
extraction. A pressure gauge (0-±30 psi), obtained from Fisher
Scientific, was used to record the pressure.

Synthesis of VHIM Ionic Liquids (IL) Monomers

[0442] The ionic liquid monomers were synthesized, as shown in FIG. 41.
Briefly, 1-vinyl-3-hexylimidazolium bromide (VHIM-Br) was produced by
mixing 1-vinylimidazole with an equimolar amount of 1-bromohexane in
2-propanol. The mixture was then allowed to react at 60° C. under
constant stirring for 24 h. After removal of 2-propanol under vacuum, the
product was dissolved in small amount of Milli-Q water and then extracted
with ethyl acetate five times to remove any unreacted starting materials.
Ethyl acetate was then removed, and product was collected and dried in a
vacuum oven. The purity of the VHIM-Br was confirmed by 1H-NMR
before polymerization or metathesis anion exchange.

Synthesis of VHIM Ionic Liquids Polymers (PIL)

[0443] To obtain poly(1-vinyl-3-hexylimidazolium)
bis[(trifluoromethyl)sulfonyl]imide (poly(VHIM-NTf2)),
polymerization of VHIM-Br was carried out by free radical polymerization,
as shown in FIG. 42. Briefly, 5.0 g of the purified VHIM-Br was dissolved
in 30 mL of chloroform. Then, 0.1 g (˜2%) of the free radical
initiator AIBN (2,2'-azo-bis(isobutyronitrile)) was introduced, and the
solution was refluxed for 3 h under N2 protection. Chloroform was
then removed under vacuum and the product was dried in a vacuum oven. The
polymerization step was proved to be completed by the disappearance of
the peaks that represent the vinyl group in the 1H-NMR. The
polymerization was repeated when necessary. The obtained
poly(1-vinyl-3-hexylimidazolium) bromide was dissolved in Milli-Q water
and equimolar amount of lithium bis[(trifluoromethyl)sulfonyl]imide
(LiNTf2) was introduced to this aqueous solution to perform
metathesis anion exchange. This solution was stirred overnight, and the
resulting polymeric ionic liquid (PIL) precipitate, poly(VHIM-NTf2),
was collected and washed with 3 aliquots of water and then dried under
vacuum at 70° C. for 2 days.

Synthesis of poly(VHIM-taurate)

[0444] To synthesize poly(1-vinyl-3-hexylimidazolium) taurate, the counter
anion of VHIM-Br was changed to hydroxide by passing the monomer through
a column packed with ion-exchange resin in the hydroxide ion form, as
shown in FIG. 43. Particularly, 100 mL of the regenerated ion-exchange
resin was packed into a 50×2 cm column followed by flushing excess
5 M NaOH to ensure the resin was completely switched to the hydroxide ion
form. This was verified by adding silver nitrate to a collected fraction
of the eluent. White silver bromide precipitate forms if bromide ions
persist in the solution. Nitric acid was used to avoid the potential
interference of silver oxide, which is a dark precipitate and can be
dissolved by introducing nitric acid. After regenerating the resin
completely, VHIM-Br was dissolved in water and passed through the
ion-exchange resin column with an appropriate flow rate.

[0445] The generated hydroxide-based IL was kept in aqueous solution, due
to its limited stability. An acid-base titration was applied to determine
the concentration of the hydroxide-based IL in the aqueous solution. The
final step was a neutralization reaction between VHIM-OH and taurine. An
equimolar amount of taurine was dissolved in water and added into the
VHIM-OH aqueous solution drop-by-drop to avoid intense reaction. The
reaction was completed overnight. Water was consequently removed by
rotary evaporation, and the product was dried under vacuum for 48 h. NMR
spectra were obtained to verify the structure of VHIM-taurate.
Polymerization was performed using the aforementioned conditions to yield
the poly(1-vinyl-3-hexylimidazolium) taurate [poly(VHIM-taurate)] PIL.

Preparation of PIL-Coated SPME Fibers

[0446] Laboratory-made SPME devices were constructed. Pre-treated SPME
fibers were coated with the poly(VHIM-NTf2) PIL, poly(VHIM-taurate)
PIL, as well as mixtures containing these two PILs. To prepare a binary
fiber coating mixture of PILs, poly(VHIM-NTf2) and
poly(VHIM-taurate) were mixed in chloroform at the desired weight
percentages of each component. The coating solution was shaken for 5 min
to ensure that the two PILs were homogeneously mixed. The film thickness
of the PIL fibers coating were estimated by scanning electron microscopy.

[0447] Extraction of CO2

[0448] The apparatus used is shown in FIG. 43. The operation of the SPME
set-up was performed according to the following steps:

[0449] (1) With the regulator closed, valve 1 and valve 2 were opened, and
the entire system evacuated until the pressure reading from the pressure
meter was constant.

[0450] (2) Valve 1 was closed to isolate the system from the atmosphere.
The initial pressure was recorded from the pressure gauge.

[0451] (3) The regulator was open to introduce the gas sample to the
sample bulb. The reading from the pressure gauge was recorded as the
final pressure when the pressure reached a constant value.

[0452] (4) Valve 2 was closed and the SPME fiber exposed to the gas sample
inside the sample bulb for a desired length of time.

[0453] (5) The captured CO2 was released from SPME fiber by high
temperature desorption in the GC injection port, and the obtained
CO2 peak area normalized by ΔP (final pressure-initial
pressure).

[0454] GC Separation

[0455] All separation experiments were conducted using an Agilent
Technologies 6890N gas chromatograph (Agilent Technologies, Palo Alto,
Calif., USA). The gas chromatograph is equipped with thermal conductivity
and flame ionization detectors coupled in series. All separations were
performed using a Carboxen 1010 PLOT capillary column (30 m×0.32 mm
I.D.) purchased from Supelco. The following temperature program was used
for the separation of CO2: initial temperature of 35° C. held
for 10 min and then increased to 225° C. employing a ramp of
12° C./min. Helium was used as the carrier gas with a flow rate of
1 mL/min. The inlet temperature was maintained at 250° C. for
PDMS, Carboxen®-PDMS and poly(VHIM-NTf2) PIL fibers, and
180° C. for the other fibers. A splitless injection was used, and
a purge flow to split vent of 20.0 mL/min at 0.10 min was applied. The
thermal conductivity detectors were held at 250° C., reference
flow of 20.0 mL/min and the make-up flow of helium at 7.0 mL/min. Agilent
Chemstation software was used for data acquisition.

[0460] FIG. 50: Sorption-time profile obtained under low pressure of
CO2 showing the comparison of different IL-based sorbent coatings to
2 commercial-based coatings (Carboxen and PDMS). The film thicknesses of
the two commercial coatings are approximately six to seven times that of
the IL-based systems.

[0461] FIG. 51: Sorption-time profile obtained under high pressure of
CO2 showing the comparison of different IL-based sorbent coatings to
2 commercial-based coatings (Carboxen and PDMS). The film thickness of
the two commercial coatings are approximately six to seven times that of
the IL-based systems.

[0463] FIG. 53: Chart showing relative standard deviation values
demonstrating the enhanced reproducibility of two IL-based polymer
coatings compared to two commercial-based sorbent coatings. The time in
parenthesis represents the time during the extraction step in which the
fiber was withdrawn and subjected to GC analysis.

[0465] Absorbent coatings comprised completely of ions have interesting
properties not observed with traditional SPME and SBSE coating materials.
The selectivity and utility of ILs can be realized by understanding the
tunability offered by ion exchange processes.

Example B

Example 13

[0466] Selectivity Tuning by on-Support Anion Exchange.

[0467] The cation and anion each contribute unique solvation interactions
thereby making ILs among the most complex solvents. In most traditional
imidazolium-based ILs, the anion provides the IL its hydrogen-bond basic
behavior. The synthesis of ILs can involve the construction of the
cationic portion of the molecule followed by metathesis anion exchange.
Using this approach, on-fiber metathesis exchange of anions from
immobilized absorbents on both stir bar and fused silica supports can be
produced.

[0468] This method, shown schematically in FIG. 26, requires that the IL
coating be partially crosslinked to allow swelling of the polymer for
complete metathesis exchange. This can be accomplished using a similar
approach that has been used for polymer beads resulting from partially
crosslinking vinyl-functionalized IL monomers.

[0469] On-fiber anion exchange can allow for high throughput
characterization of IL-polymers as well as provide a simple route for
altering the extraction selectivity of the absorbent coating.

Example B

Example 14

[0470] DNA Extractions Using Ionic Liquids

[0471] One of the most commonly employed methods of isolating and
concentrating DNA and RNA from aqueous solution is the buffer-saturated
phenol/chloroform extraction system. Protein contaminants become
denatured in the presence of the organic solvent and typically partition
into the organic phase while the nucleic acid resides in the aqueous
phase. Recently, the first ever extraction of DNA into the IL
BMIM-PF6.sup.- (1-butyl-3-methylimidazolium hexafluorophosphate) was
demonstrated where 30% of the DNA could be back extracted into an aqueous
buffered solution using a single stage extraction. It was also found that
the IL used preferentially partitioned the nucleic acid over
contaminating proteins and metal species. Using NMR and IR, the
interactions between the cationic BMIM+ and phosphate groups within
the DNA acted to facilitate the extraction into the IL.

[0472] The presently described support-assisted strategy of extracting
analytes from solutions, can be used for the partitioning of
double-stranded DNA into PILs. For example, imidazolium-based PILs with
the hexafluorophosphate and bis[(trifluoromethyl)sulfonlyl]imide anions,
can be used since most of these PILs are water immiscible. The cation
structure can be varied using different lengths of alkyl chains on the 1
and 3 positions of the imidazolium ring (see FIG. 30A) while maintaining
liquids at room temperature.

[0473] Following extraction of the nucleic acids, the IL can be introduced
into an HPLC using a solvent desorption chamber.

[0474] The results obtained using the methods and ILs described herein are
also useful in ion exchange mechanisms responsible for the extraction of
nucleic acids and can extend the realm of ionic liquids and separation
science into the mainstream of biology and biochemistry.

[0476] Static headspace-gas chromatography (HS-GC) is a common approach
used for the analysis of analytes in the vapor phase that are in
equilibrium with a solid or liquid phase. In the sampling of less
volatile analytes, it is often necessary to thermostat the liquid or
solid phase at elevated temperatures, thereby increasing the equilibrium
amount of analyte present in the headspace. However, heating of the
sample often causes partial vaporization of the solvent, resulting in
increased pressure build-up within the sample vial. For that reason, it
has been stated that the vapor pressure of the extracting solvent
dramatically affects the enrichment factor achieved in HS-GC.

[0477] The inventors herein demonstrate the versatility of ILs in
separation science by introducing a HS-SPME-GC extraction/separation
method in which carefully designed ILs are used as (1) a sample solvent
for hydrocarbons and fatty acid methyl esters (FAMEs) possessing high
boiling points (higher than 380° C.) and low vapor pressures, (2)
high selectivity SPME sorbent coating for the HS extraction of analytes,
and (3) low-bleed, high selectivity stationary phase for GC. Each IL has
been independently structurally engineered so that the imparted physical
and chemical properties are compatible with the requirements of each
component of the method thereby producing a robust method in terms of
overall analytical performance. To the inventors' knowledge, this is the
first report in which these analytes have been successfully quantified by
HS-GC.

[0478] Materials

[0479] The six analytes determined in this work were purchased from
Sigma-Aldrich (Milwaukee, Wis., USA). Their molecular structures, boiling
points, and vapor pressures are

[0482] The coating of the GC column with the high stability IL was
performed using the static method on a fifteen-meter capillary column
(0.25 mm I.D). The coating method utilized a 0.25% (w/v) solution of the
dicationic IL 1,12-Di-(3-butylimidazolium)dodecane
bis[(trifluoromethyl)sulfonyl]imide [C12(BIM)2] [NTf2]
(shown in FIG. 52) in methylene chloride at 40° C. The synthesis
of this dicationic IL was carried out. Coated capillaries were
conditioned overnight from 40° C. to 100° C. at 1°
C.min-1 using a constant flow of helium at a flow rate of 1.0
mLmin-1. Column efficiency was tested with naphthalene at
120° C. The column possessed an efficiency of 1554 platesm-1
at 120° C., and was tested weekly to ensure that the efficiency
remained constant.

[0483] All GC experiments were conducted using an Agilent Technologies
6890N gas chromatograph (Palo Alto, Calif., USA). The gas chromatograph
was equipped with thermal conductivity (TCD) and flame ionization (FID)
detectors coupled in series. Helium was used as the carrier gas with a
flow rate of 1 mLmin-1. The inlet and detector temperatures were
operated at 250° C. Splitless injection was used during all
experiments. The make-up flow of helium was maintained at 45
mLmin-1, the hydrogen flow at 40 mLmin-1, and the air flow at
450 mLmin-1. The following temperature program was used in the
separation of the analytes: the initial temperature of 150° C. was
held for 4 minutes, then raised to 160° C. at a ramp of 10°
C.min-1 and held for 2 minutes, and then raised to 170° C. at
a speed of 10° C.min-1 and held for 5 minutes. Afterwards, a
10° C.min-1 ramp was used to increase the oven temperature to
180° C. and was held for another 5 minutes. Finally, the
temperature of the oven was raised to 195° C. using a ramp of
15° C.min-1 and was held for 15 minutes. Agilent ChemStation
software was used for data acquisition.

[0484] The preparation of the PIL-based SPME coating involved the
synthesis of the poly[ViHDIM] [NTf2] PIL (see structure in FIG. 52)
followed by the preparation of fibers. The film thickness of the coating
was in the range of 10-15 μm, as estimated by optical microscopy. The
desorption time for the fiber in the GC injector was fixed at 5 minutes
in all experiments.

[0485] A stock solution was prepared by dissolving 2 mg of each of the
analytes into 40 g of the [HMIM] [FAP] IL, which was dried in a vacuum
oven at 70° C. overnight before use. The stock solution was
maintained at approximately 60° C. in order to ensure a homogenous
mixture. The working solution was prepared by diluting different amounts
of the stock solution with pure [HMIM] [FAP] to various concentrations.
The total mass of the working solution was maintained at 400 mg in the
sample vial and the volume of the headspace was 1.5 mL for all
extractions. The sorption-time profiles were obtained by immersion of the
PIL coated fiber into the headspace of the working standard solution
containing the studied analytes at a concentration of 25 mg of analyte
per kg of [HMIM] [FAP], using different extraction times (from 15 to 150
min) while stiffing at 170±10° C.

[0486] FIG. 53 shows a detailed schematic of the extraction and separation
system utilized. Static headspace extractions were performed by first
piercing the sampling vial containing the IL/analyte mixture and stir bar
with the syringe housing the SPME fiber. The sampling vial was then
positioned in the heated silicone oil bath followed by stirring of the
IL/analyte mixture using a magnetic stirrer. The SPME fiber was then
exposed to the headspace of the sampling mixture. In order to minimize
large temperature variations throughout the extraction, an overhead
mechanical stirrer was used to stir the oil bath. Following the
extraction, the SPME fiber was withdrawn into the syringe, the syringe
removed from the vial, and the fiber thermally desorbed in the GC
injector thereby subjecting the analytes to the IL-based stationary phase
for separation.

[0488] To function as an effective solvent in headspace extraction
studies, an IL should possess the following features: (1) be chemically
unreactive with analytes being examined, (2) exhibit high thermal
stability, (3) ability to dissolve the analytes in the concentration
range needed for making adequate calibration curves, and (4) exhibit
reasonably low viscosity to facilitate the preparation of samples and
standards as well as to ensure efficient sample agitation during
extraction. Merck KGaA has recently developed a class of hydrophobic ILs
that exhibit much lower water uptake than commonly studied
NTf2.sup.- and hexafluorophosphate-based ILs. ILs containing this
unique anion exhibit viscosities comparable to the NTf2anions. Thermal gravimetric analysis of this class of ILs has revealed
that imidazolium-based ILs decompose at temperatures above 280° C.
The solubility of the analytes in the [HMIM] [FAP] IL was found to be
acceptable in the range up to 50 mg of analyte per kg of IL.

[0490] The polymeric nature of PIL compounds provides them additional
thermal stability as well as exceptional film stability, thereby
producing high extraction-to-extraction reproducibility and lifetimes
comparable to commercially coated fibers. The selectivity of PIL-based
coatings can be modulated by introducing functional groups to the
cationic portion of the IL or by incorporating different anions to impart
desired solvent characteristics.

[0491] The poly[ViHDIM] [NTf2] PIL was chosen in the Example as it
undergoes stronger dispersion-type interactions with the analytes thus
producing high extraction efficiencies.

[0493] ILs have been shown to be highly selective stationary phases for
GC. To fulfill the requirements of this component for this study, a
relatively nonpolar stationary phase possessing low bleed at elevated
temperatures was required. The dicationic IL
[C12(BIM)2][NTf2] was chosen as it has been shown
previously to exhibit high thermal stability, a wide liquid range, and
broader selectivities compared to many traditional classes of
monocationic ILs.

[0494] Synergy of Three IL-Based Components in Extraction/Separation
System

[0495] The analytes extracted in this work include three hydrocarbons:
tricosane, hexacosane, and triacontane; and three fatty acid methyl
esters: methyl behenate, methyl heneicosanoate, and methyl
tetracosanoate. These analytes were dissolved in the [HMIM] [FAP] IL and
then extracted by HS-SPME-GC. In order to achieve adequate extraction
efficiencies using the HS-SPME method, high temperature is required for
these less volatile analytes. However, the sorption of the analytes to
the SPME coating is an exothermic process, and as the temperature
increases, the analyte to coating partition coefficient decreases.
Therefore, the temperature must be optimized so that the decrease of the
partition coefficient is offset by the increase in the equilibrium
concentration of the analytes in the headspace to achieve reasonable
extraction efficiencies. The optimized extraction temperature was
170±10° C. The extraction time and temperature in several
previously reported studies involving headspace applications for less
volatile analytes (with by ranging from 152 to 228° C.) are: 10
minutes at 110° C., 15 minutes at 100° C., and 15 minutes
at 150 or 180° C., depending on the analyte.

[0496] Sorption-time profiles were generated by performing the extraction
at various time intervals to identify the equilibration time using the
optimum temperature. FIG. 54 shows the sorption-time profiles obtained by
plotting the analyte peak area versus the extraction time. Tricosane and
hexacosane reach equilibrium at around 60 minutes whereas the remaining
analytes reach equilibrium in around 100 min. An extraction time of 100
min was considered as the optimum extraction time. The comparison of the
extraction efficiencies for the hydrocarbons and FAMEs can also be
observed in FIG. 54. With respect to the hydrocarbons, the lightest
hydrocarbon (tricosane) exhibits the highest extraction efficiency
whereas the lowest extraction efficiency is seen with the heaviest
hydrocarbon, triacontane. The same trend is observed with the three
FAMEs, although their extraction efficiencies are much lower compared to
the studied hydrocarbons. The trend in the extraction efficiency is
consistent with the vapor pressures and boiling points of these analytes
(see EXAMPLE C Table 1).

Example C

Example 2

[0497] Analytical Performance of the Method

[0498] Calibration curves were obtained using working standard solutions
of analytes in the [HMIM] [FAP] IL at different concentrations while
performing the extraction at the optimum extraction time and temperature.
The figures of merit for the entire method, shown in EXAMPLE C Table 2,
include the sensitivity, calibration range, correlation coefficients,
error of the estimate and limits of detection.

[0499] The obtained linearity of the overall method was found to be
acceptable, with correlation coefficients (R) ranging from 0.990 to
0.998. The sensitivity, which can be evaluated by the slope, is higher
for the hydrocarbons, particularly for tricosane, than for the FAMEs. It
can be clearly observed that the sensitivity decreased with increasing
carbon chain length of the hydrocarbons and FAMEs. The limits of
detection varied from 0.1 mgkg-1 for tricosane to 0.6 mgkg-1
for methyl tetracosanoate. This constitutes the first report of a
headspace extraction approach for these particular analytes. However,
other analytes possessing high boiling points have been determined
previously by headspace extraction. They include N,N-dimethylformamide
(DMF), N-methyl-2-pyrrolidine (NPM), propylene glycol (PG), formamide,
tri-n-butylamine (tBA), and 2-ethylhexanoic acid (2EHA). The boiling
points for these analytes are in the range 152-228° C. and the
reported detection limits for these analytes are 53 mgL-1 or 1-90
mgL-1 depending on the IL solvent for DMF; 2.5 mgL-1 or 1-100
mgL-1 depending on IL solvent for NMP; 13 mgL-1 for formamide;
8 mgL-1 for tBA; and 22 mgL-1 for 2EHA. For comparison, the
analytes determined in this method possess boiling points in the range
380-450° C. with detection limits less than 0.6 mgkg-1.

[0500] The reproducibility of the method was evaluated by carrying out a
series of extractions using working standard solutions of the analytes at
two different concentration levels, namely, 4 and 20 mg of analyte per kg
of [HMIM] [FAP] IL. The obtained results can be observed in EXAMPLE
C--Table 3.

[0501] The relative standard deviation ranged from 11 to 22% for the lower
spiking level (4 mgkg-1), and from 5.9 to 16% for the higher spiking
level (20 mgkg-1). This precision reflects all of the errors in the
overall method, including the temperature fluctuations that occur during
SPME. The extraction efficiency, expressed as relative recoveries, varied
from 78.5 to 122% at the lower spiking level and from 69.9 to 106% at the
higher spiking level. Under the extreme extraction temperatures and times
used in this study, the fiber lifetime dropped to approximately 30
extractions before the extraction-to-extraction reproducibility decreased
dramatically. Finally, the performance of the GC column comprised of the
[C12(BIM)2] [NTf2] IL stationary phase was evaluated. A
sample chromatogram of the six analytes separated on this stationary
phase is shown as supporting information. The reproducibility of the
analyte retention times during the study produced RSD values ranging from
0.9 to 2.6% (n=60).

Conclusions

[0502] One of the most interesting and useful characteristics of ILs lies
with their vast structural tuneability which provides a wealth of
opportunities in adapting the physical and chemical properties of the
material for applications in separation science. Herein, an analytical
method utilizing three distinct and separate IL components was used to
perform high temperature headspace extraction and separation of six
analytes possessing high boiling points and low vapor pressures. The
[HMIM] [FAP] IL has been shown to be an excellent solvent in that the
hydrophobic and refractory nature of the IL promotes dissolution of the
apolar analytes while avoiding pressure build-up within the sample vial
under extreme temperatures. As a selective sorbent coating for SPME, the
PIL component exhibits acceptable extraction efficiency of the studied
analytes under the extreme experimental conditions. Finally, the
structural design of the IL-based GC stationary phase produces a
thermally stabile material that exhibits high separation selectivity of
the analytes while producing minimal column bleed. The overall method
nicely demonstrates the versatility of ILs within separation science for
the determination of low volatility analytes using headspace extraction
mode with detection limits ranging from 0.3 to 0.6 mgkg-1, relative
recoveries ranging from 69.9% to 106%, and precision values between 5.9
and 22% as relative standard deviation. This method may be particularly
useful for monitoring reaction products formed during catalysis
experiments when ILs are used as the reaction solvent. Future work will
involve the use of blended ILs and task-specific ILs to further improve
the sensitivity and reproducibility of the overall method.

[0503] While the specification concludes with the claims particularly
pointing out and distinctly claiming the invention, it is believed that
the present invention will be better understood from the following
description. All percentages and ratios used herein are by weight of the
total composition and normal pressure unless otherwise designated. All
temperatures are in Degrees Celsius unless specified otherwise. The
present invention can comprise (open ended) or consist essentially of the
components of the present invention as well as other ingredients or
elements described herein. As used herein, "comprising" means the
elements recited, or their equivalent in structure or function, plus any
other element or elements which are not recited. The terms "having" and
"including" are also to be construed as open ended unless the context
suggests otherwise. As used herein, "consisting essentially of" means
that the invention may include ingredients in addition to those recited
in the claim, but only if the additional ingredients do not materially
alter the basic and novel characteristics of the claimed invention.
Preferably, such additives will not be present at all or only in trace
amounts. However, it may be possible to include up to about 10% by weight
of materials that could materially alter the basic and novel
characteristics of the invention as long as the utility of the compounds
(as opposed to the degree of utility) is maintained. All ranges recited
herein include the endpoints, including those that recite a range
"between" two values. Terms such as "about," "generally,"
"substantially," and the like are to be construed as modifying a term or
value such that it is not an absolute, but does not read on the prior
art. Such terms will be defined by the circumstances and the terms that
they modify as those terms are understood by those of skill in the art.
This includes, at very least, the degree of expected experimental error,
technique error and instrument error for a given technique used to
measure a value

[0504] Certain embodiments of the present invention are defined in the
Examples herein, in which all parts and percentages are by weight and
degrees are Celsius, unless otherwise stated. It should be understood
that these Examples, while indicating preferred embodiments of the
invention, are given by way of illustration only. From the above
discussion and these Examples, one skilled in the art can ascertain the
essential characteristics of this invention, and without departing from
the spirit and scope thereof, can make various changes and modifications
of the invention to adapt it to various usages and conditions. All
publications, including patents and non-patent literature, referred to in
this specification are expressly incorporated by reference herein.

[0505] While the invention has been described with reference to various
and preferred embodiments, it should be understood by those skilled in
the art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the essential
scope of the invention. In addition, many modifications may be made to
adapt a particular situation or material to the teachings of the
invention without departing from the essential scope thereof.

[0506] Therefore, it is intended that the invention not be limited to the
particular embodiment disclosed herein contemplated for carrying out this
invention, but that the invention will include all embodiments falling
within the scope of the claims.

REFERENCES

[0507] The publication and other material used herein to illuminate the
invention or provide additional details respecting the practice of the
invention, are incorporated be reference herein, and for convenience are
provided in the following bibliography.

[0508] Citation of the any of the documents recited herein is not intended
as an admission that any of the foregoing is pertinent prior art. All
statements as to the date or representation as to the contents of these
documents is based on the information available to the applicant and does
not constitute any admission as to the correctness of the dates or
contents of these documents.